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          <h1>Node.js v14.19.1 documentation</h1>
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      <details id="toc" open><summary>Table of contents</summary><ul>
<li><span class="stability_2"><a href="#crypto_crypto">Crypto</a></span>
<ul>
<li><a href="#crypto_determining_if_crypto_support_is_unavailable">Determining if crypto support is unavailable</a></li>
<li><a href="#crypto_class_certificate">Class: <code>Certificate</code></a>
<ul>
<li><a href="#crypto_certificate_exportchallenge_spkac"><code>Certificate.exportChallenge(spkac)</code></a></li>
<li><a href="#crypto_certificate_exportpublickey_spkac_encoding"><code>Certificate.exportPublicKey(spkac[, encoding])</code></a></li>
<li><a href="#crypto_certificate_verifyspkac_spkac"><code>Certificate.verifySpkac(spkac)</code></a></li>
<li><span class="stability_0"><a href="#crypto_legacy_api">Legacy API</a></span>
<ul>
<li><a href="#crypto_new_crypto_certificate"><code>new crypto.Certificate()</code></a></li>
<li><a href="#crypto_certificate_exportchallenge_spkac_1"><code>certificate.exportChallenge(spkac)</code></a></li>
<li><a href="#crypto_certificate_exportpublickey_spkac"><code>certificate.exportPublicKey(spkac)</code></a></li>
<li><a href="#crypto_certificate_verifyspkac_spkac_1"><code>certificate.verifySpkac(spkac)</code></a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#crypto_class_cipher">Class: <code>Cipher</code></a>
<ul>
<li><a href="#crypto_cipher_final_outputencoding"><code>cipher.final([outputEncoding])</code></a></li>
<li><a href="#crypto_cipher_getauthtag"><code>cipher.getAuthTag()</code></a></li>
<li><a href="#crypto_cipher_setaad_buffer_options"><code>cipher.setAAD(buffer[, options])</code></a></li>
<li><a href="#crypto_cipher_setautopadding_autopadding"><code>cipher.setAutoPadding([autoPadding])</code></a></li>
<li><a href="#crypto_cipher_update_data_inputencoding_outputencoding"><code>cipher.update(data[, inputEncoding][, outputEncoding])</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_decipher">Class: <code>Decipher</code></a>
<ul>
<li><a href="#crypto_decipher_final_outputencoding"><code>decipher.final([outputEncoding])</code></a></li>
<li><a href="#crypto_decipher_setaad_buffer_options"><code>decipher.setAAD(buffer[, options])</code></a></li>
<li><a href="#crypto_decipher_setauthtag_buffer"><code>decipher.setAuthTag(buffer)</code></a></li>
<li><a href="#crypto_decipher_setautopadding_autopadding"><code>decipher.setAutoPadding([autoPadding])</code></a></li>
<li><a href="#crypto_decipher_update_data_inputencoding_outputencoding"><code>decipher.update(data[, inputEncoding][, outputEncoding])</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_diffiehellman">Class: <code>DiffieHellman</code></a>
<ul>
<li><a href="#crypto_diffiehellman_computesecret_otherpublickey_inputencoding_outputencoding"><code>diffieHellman.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])</code></a></li>
<li><a href="#crypto_diffiehellman_generatekeys_encoding"><code>diffieHellman.generateKeys([encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_getgenerator_encoding"><code>diffieHellman.getGenerator([encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_getprime_encoding"><code>diffieHellman.getPrime([encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_getprivatekey_encoding"><code>diffieHellman.getPrivateKey([encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_getpublickey_encoding"><code>diffieHellman.getPublicKey([encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_setprivatekey_privatekey_encoding"><code>diffieHellman.setPrivateKey(privateKey[, encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_setpublickey_publickey_encoding"><code>diffieHellman.setPublicKey(publicKey[, encoding])</code></a></li>
<li><a href="#crypto_diffiehellman_verifyerror"><code>diffieHellman.verifyError</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_diffiehellmangroup">Class: <code>DiffieHellmanGroup</code></a></li>
<li><a href="#crypto_class_ecdh">Class: <code>ECDH</code></a>
<ul>
<li><a href="#crypto_static_method_ecdh_convertkey_key_curve_inputencoding_outputencoding_format">Static method: <code>ECDH.convertKey(key, curve[, inputEncoding[, outputEncoding[, format]]])</code></a></li>
<li><a href="#crypto_ecdh_computesecret_otherpublickey_inputencoding_outputencoding"><code>ecdh.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])</code></a></li>
<li><a href="#crypto_ecdh_generatekeys_encoding_format"><code>ecdh.generateKeys([encoding[, format]])</code></a></li>
<li><a href="#crypto_ecdh_getprivatekey_encoding"><code>ecdh.getPrivateKey([encoding])</code></a></li>
<li><a href="#crypto_ecdh_getpublickey_encoding_format"><code>ecdh.getPublicKey([encoding][, format])</code></a></li>
<li><a href="#crypto_ecdh_setprivatekey_privatekey_encoding"><code>ecdh.setPrivateKey(privateKey[, encoding])</code></a></li>
<li><span class="stability_0"><a href="#crypto_ecdh_setpublickey_publickey_encoding"><code>ecdh.setPublicKey(publicKey[, encoding])</code></a></span></li>
</ul>
</li>
<li><a href="#crypto_class_hash">Class: <code>Hash</code></a>
<ul>
<li><a href="#crypto_hash_copy_options"><code>hash.copy([options])</code></a></li>
<li><a href="#crypto_hash_digest_encoding"><code>hash.digest([encoding])</code></a></li>
<li><a href="#crypto_hash_update_data_inputencoding"><code>hash.update(data[, inputEncoding])</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_hmac">Class: <code>Hmac</code></a>
<ul>
<li><a href="#crypto_hmac_digest_encoding"><code>hmac.digest([encoding])</code></a></li>
<li><a href="#crypto_hmac_update_data_inputencoding"><code>hmac.update(data[, inputEncoding])</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_keyobject">Class: <code>KeyObject</code></a>
<ul>
<li><a href="#crypto_keyobject_asymmetrickeytype"><code>keyObject.asymmetricKeyType</code></a></li>
<li><a href="#crypto_keyobject_export_options"><code>keyObject.export([options])</code></a></li>
<li><a href="#crypto_keyobject_symmetrickeysize"><code>keyObject.symmetricKeySize</code></a></li>
<li><a href="#crypto_keyobject_type"><code>keyObject.type</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_sign">Class: <code>Sign</code></a>
<ul>
<li><a href="#crypto_sign_sign_privatekey_outputencoding"><code>sign.sign(privateKey[, outputEncoding])</code></a></li>
<li><a href="#crypto_sign_update_data_inputencoding"><code>sign.update(data[, inputEncoding])</code></a></li>
</ul>
</li>
<li><a href="#crypto_class_verify">Class: <code>Verify</code></a>
<ul>
<li><a href="#crypto_verify_update_data_inputencoding"><code>verify.update(data[, inputEncoding])</code></a></li>
<li><a href="#crypto_verify_verify_object_signature_signatureencoding"><code>verify.verify(object, signature[, signatureEncoding])</code></a></li>
</ul>
</li>
<li><a href="#crypto_crypto_module_methods_and_properties"><code>crypto</code> module methods and properties</a>
<ul>
<li><a href="#crypto_crypto_constants"><code>crypto.constants</code></a></li>
<li><span class="stability_0"><a href="#crypto_crypto_default_encoding"><code>crypto.DEFAULT_ENCODING</code></a></span></li>
<li><span class="stability_0"><a href="#crypto_crypto_fips"><code>crypto.fips</code></a></span></li>
<li><span class="stability_0"><a href="#crypto_crypto_createcipher_algorithm_password_options"><code>crypto.createCipher(algorithm, password[, options])</code></a></span></li>
<li><a href="#crypto_crypto_createcipheriv_algorithm_key_iv_options"><code>crypto.createCipheriv(algorithm, key, iv[, options])</code></a></li>
<li><span class="stability_0"><a href="#crypto_crypto_createdecipher_algorithm_password_options"><code>crypto.createDecipher(algorithm, password[, options])</code></a></span></li>
<li><a href="#crypto_crypto_createdecipheriv_algorithm_key_iv_options"><code>crypto.createDecipheriv(algorithm, key, iv[, options])</code></a></li>
<li><a href="#crypto_crypto_creatediffiehellman_prime_primeencoding_generator_generatorencoding"><code>crypto.createDiffieHellman(prime[, primeEncoding][, generator][, generatorEncoding])</code></a></li>
<li><a href="#crypto_crypto_creatediffiehellman_primelength_generator"><code>crypto.createDiffieHellman(primeLength[, generator])</code></a></li>
<li><a href="#crypto_crypto_creatediffiehellmangroup_name"><code>crypto.createDiffieHellmanGroup(name)</code></a></li>
<li><a href="#crypto_crypto_createecdh_curvename"><code>crypto.createECDH(curveName)</code></a></li>
<li><a href="#crypto_crypto_createhash_algorithm_options"><code>crypto.createHash(algorithm[, options])</code></a></li>
<li><a href="#crypto_crypto_createhmac_algorithm_key_options"><code>crypto.createHmac(algorithm, key[, options])</code></a></li>
<li><a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey(key)</code></a></li>
<li><a href="#crypto_crypto_createpublickey_key"><code>crypto.createPublicKey(key)</code></a></li>
<li><a href="#crypto_crypto_createsecretkey_key"><code>crypto.createSecretKey(key)</code></a></li>
<li><a href="#crypto_crypto_createsign_algorithm_options"><code>crypto.createSign(algorithm[, options])</code></a></li>
<li><a href="#crypto_crypto_createverify_algorithm_options"><code>crypto.createVerify(algorithm[, options])</code></a></li>
<li><a href="#crypto_crypto_diffiehellman_options"><code>crypto.diffieHellman(options)</code></a></li>
<li><a href="#crypto_crypto_generatekeypair_type_options_callback"><code>crypto.generateKeyPair(type, options, callback)</code></a></li>
<li><a href="#crypto_crypto_generatekeypairsync_type_options"><code>crypto.generateKeyPairSync(type, options)</code></a></li>
<li><a href="#crypto_crypto_getciphers"><code>crypto.getCiphers()</code></a></li>
<li><a href="#crypto_crypto_getcurves"><code>crypto.getCurves()</code></a></li>
<li><a href="#crypto_crypto_getdiffiehellman_groupname"><code>crypto.getDiffieHellman(groupName)</code></a></li>
<li><a href="#crypto_crypto_getfips"><code>crypto.getFips()</code></a></li>
<li><a href="#crypto_crypto_gethashes"><code>crypto.getHashes()</code></a></li>
<li><a href="#crypto_crypto_pbkdf2_password_salt_iterations_keylen_digest_callback"><code>crypto.pbkdf2(password, salt, iterations, keylen, digest, callback)</code></a></li>
<li><a href="#crypto_crypto_pbkdf2sync_password_salt_iterations_keylen_digest"><code>crypto.pbkdf2Sync(password, salt, iterations, keylen, digest)</code></a></li>
<li><a href="#crypto_crypto_privatedecrypt_privatekey_buffer"><code>crypto.privateDecrypt(privateKey, buffer)</code></a></li>
<li><a href="#crypto_crypto_privateencrypt_privatekey_buffer"><code>crypto.privateEncrypt(privateKey, buffer)</code></a></li>
<li><a href="#crypto_crypto_publicdecrypt_key_buffer"><code>crypto.publicDecrypt(key, buffer)</code></a></li>
<li><a href="#crypto_crypto_publicencrypt_key_buffer"><code>crypto.publicEncrypt(key, buffer)</code></a></li>
<li><a href="#crypto_crypto_randombytes_size_callback"><code>crypto.randomBytes(size[, callback])</code></a></li>
<li><a href="#crypto_crypto_randomfillsync_buffer_offset_size"><code>crypto.randomFillSync(buffer[, offset][, size])</code></a></li>
<li><a href="#crypto_crypto_randomfill_buffer_offset_size_callback"><code>crypto.randomFill(buffer[, offset][, size], callback)</code></a></li>
<li><a href="#crypto_crypto_randomint_min_max_callback"><code>crypto.randomInt([min, ]max[, callback])</code></a></li>
<li><a href="#crypto_crypto_randomuuid_options"><code>crypto.randomUUID([options])</code></a></li>
<li><a href="#crypto_crypto_scrypt_password_salt_keylen_options_callback"><code>crypto.scrypt(password, salt, keylen[, options], callback)</code></a></li>
<li><a href="#crypto_crypto_scryptsync_password_salt_keylen_options"><code>crypto.scryptSync(password, salt, keylen[, options])</code></a></li>
<li><a href="#crypto_crypto_setengine_engine_flags"><code>crypto.setEngine(engine[, flags])</code></a></li>
<li><a href="#crypto_crypto_setfips_bool"><code>crypto.setFips(bool)</code></a></li>
<li><a href="#crypto_crypto_sign_algorithm_data_key"><code>crypto.sign(algorithm, data, key)</code></a></li>
<li><a href="#crypto_crypto_timingsafeequal_a_b"><code>crypto.timingSafeEqual(a, b)</code></a></li>
<li><a href="#crypto_crypto_verify_algorithm_data_key_signature"><code>crypto.verify(algorithm, data, key, signature)</code></a></li>
</ul>
</li>
<li><a href="#crypto_notes">Notes</a>
<ul>
<li><a href="#crypto_legacy_streams_api_prior_to_node_js_0_10">Legacy streams API (prior to Node.js 0.10)</a></li>
<li><a href="#crypto_recent_ecdh_changes">Recent ECDH changes</a></li>
<li><a href="#crypto_support_for_weak_or_compromised_algorithms">Support for weak or compromised algorithms</a></li>
<li><a href="#crypto_ccm_mode">CCM mode</a></li>
</ul>
</li>
<li><a href="#crypto_crypto_constants_1">Crypto constants</a>
<ul>
<li><a href="#crypto_openssl_options">OpenSSL options</a></li>
<li><a href="#crypto_openssl_engine_constants">OpenSSL engine constants</a></li>
<li><a href="#crypto_other_openssl_constants">Other OpenSSL constants</a></li>
<li><a href="#crypto_node_js_crypto_constants">Node.js crypto constants</a></li>
</ul>
</li>
</ul>
</li>
</ul></details>

      <div id="apicontent">
        <h2>Crypto<span><a class="mark" href="#crypto_crypto" id="crypto_crypto">#</a></span></h2>

<p></p><div class="api_stability api_stability_2"><a href="documentation.html#documentation_stability_index">Stability: 2</a> - Stable</div><p></p>
<p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v14.19.1/lib/crypto.js">lib/crypto.js</a></p>
<p>The <code>crypto</code> module provides cryptographic functionality that includes a set of
wrappers for OpenSSL's hash, HMAC, cipher, decipher, sign, and verify functions.</p>
<p>Use <code>require('crypto')</code> to access this module.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> secret = <span class="hljs-string">'abcdefg'</span>;
<span class="hljs-keyword">const</span> hash = crypto.<span class="hljs-title function_">createHmac</span>(<span class="hljs-string">'sha256'</span>, secret)
                   .<span class="hljs-title function_">update</span>(<span class="hljs-string">'I love cupcakes'</span>)
                   .<span class="hljs-title function_">digest</span>(<span class="hljs-string">'hex'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hash);
<span class="hljs-comment">// Prints:</span>
<span class="hljs-comment">//   c0fa1bc00531bd78ef38c628449c5102aeabd49b5dc3a2a516ea6ea959d6658e</span></code></pre>
<section><h3>Determining if crypto support is unavailable<span><a class="mark" href="#crypto_determining_if_crypto_support_is_unavailable" id="crypto_determining_if_crypto_support_is_unavailable">#</a></span></h3>
<p>It is possible for Node.js to be built without including support for the
<code>crypto</code> module. In such cases, calling <code>require('crypto')</code> will result in an
error being thrown.</p>
<pre><code class="language-js"><span class="hljs-keyword">let</span> crypto;
<span class="hljs-keyword">try</span> {
  crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
} <span class="hljs-keyword">catch</span> (err) {
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'crypto support is disabled!'</span>);
}</code></pre>
</section><section><h3>Class: <code>Certificate</code><span><a class="mark" href="#crypto_class_certificate" id="crypto_class_certificate">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.11.8</span>
</div>
<p>SPKAC is a Certificate Signing Request mechanism originally implemented by
Netscape and was specified formally as part of <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/keygen">HTML5's <code>keygen</code> element</a>.</p>
<p><code>&#x3C;keygen></code> is deprecated since <a href="https://www.w3.org/TR/html52/changes.html#features-removed">HTML 5.2</a> and new projects
should not use this element anymore.</p>
<p>The <code>crypto</code> module provides the <code>Certificate</code> class for working with SPKAC
data. The most common usage is handling output generated by the HTML5
<code>&#x3C;keygen></code> element. Node.js uses <a href="https://www.openssl.org/docs/man1.1.0/apps/openssl-spkac.html">OpenSSL's SPKAC implementation</a> internally.</p>
<h4><code>Certificate.exportChallenge(spkac)</code><span><a class="mark" href="#crypto_certificate_exportchallenge_spkac" id="crypto_certificate_exportchallenge_spkac">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v9.0.0</span>
</div>
<ul>
<li><code>spkac</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The challenge component of the <code>spkac</code> data structure, which
includes a public key and a challenge.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Certificate</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> spkac = <span class="hljs-title function_">getSpkacSomehow</span>();
<span class="hljs-keyword">const</span> challenge = <span class="hljs-title class_">Certificate</span>.<span class="hljs-title function_">exportChallenge</span>(spkac);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(challenge.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>));
<span class="hljs-comment">// Prints: the challenge as a UTF8 string</span></code></pre>
<h4><code>Certificate.exportPublicKey(spkac[, encoding])</code><span><a class="mark" href="#crypto_certificate_exportpublickey_spkac_encoding" id="crypto_certificate_exportpublickey_spkac_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v9.0.0</span>
</div>
<ul>
<li><code>spkac</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>spkac</code> string.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The public key component of the <code>spkac</code> data structure,
which includes a public key and a challenge.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Certificate</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> spkac = <span class="hljs-title function_">getSpkacSomehow</span>();
<span class="hljs-keyword">const</span> publicKey = <span class="hljs-title class_">Certificate</span>.<span class="hljs-title function_">exportPublicKey</span>(spkac);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(publicKey);
<span class="hljs-comment">// Prints: the public key as &#x3C;Buffer ...></span></code></pre>
<h4><code>Certificate.verifySpkac(spkac)</code><span><a class="mark" href="#crypto_certificate_verifyspkac_spkac" id="crypto_certificate_verifyspkac_spkac">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v9.0.0</span>
</div>
<ul>
<li><code>spkac</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> <code>true</code> if the given <code>spkac</code> data structure is valid,
<code>false</code> otherwise.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Certificate</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> spkac = <span class="hljs-title function_">getSpkacSomehow</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Certificate</span>.<span class="hljs-title function_">verifySpkac</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(spkac)));
<span class="hljs-comment">// Prints: true or false</span></code></pre>
<h4>Legacy API<span><a class="mark" href="#crypto_legacy_api" id="crypto_legacy_api">#</a></span></h4>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated</div><p></p>
<p>As a legacy interface, it is possible to create new instances of
the <code>crypto.Certificate</code> class as illustrated in the examples below.</p>
<h5><code>new crypto.Certificate()</code><span><a class="mark" href="#crypto_new_crypto_certificate" id="crypto_new_crypto_certificate">#</a></span></h5>
<p>Instances of the <code>Certificate</code> class can be created using the <code>new</code> keyword
or by calling <code>crypto.Certificate()</code> as a function:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> cert1 = <span class="hljs-keyword">new</span> crypto.<span class="hljs-title class_">Certificate</span>();
<span class="hljs-keyword">const</span> cert2 = crypto.<span class="hljs-title class_">Certificate</span>();</code></pre>
<h5><code>certificate.exportChallenge(spkac)</code><span><a class="mark" href="#crypto_certificate_exportchallenge_spkac_1" id="crypto_certificate_exportchallenge_spkac_1">#</a></span></h5>
<div class="api_metadata">
<span>Added in: v0.11.8</span>
</div>
<ul>
<li><code>spkac</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The challenge component of the <code>spkac</code> data structure, which
includes a public key and a challenge.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> cert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>).<span class="hljs-title class_">Certificate</span>();
<span class="hljs-keyword">const</span> spkac = <span class="hljs-title function_">getSpkacSomehow</span>();
<span class="hljs-keyword">const</span> challenge = cert.<span class="hljs-title function_">exportChallenge</span>(spkac);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(challenge.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>));
<span class="hljs-comment">// Prints: the challenge as a UTF8 string</span></code></pre>
<h5><code>certificate.exportPublicKey(spkac)</code><span><a class="mark" href="#crypto_certificate_exportpublickey_spkac" id="crypto_certificate_exportpublickey_spkac">#</a></span></h5>
<div class="api_metadata">
<span>Added in: v0.11.8</span>
</div>
<ul>
<li><code>spkac</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The public key component of the <code>spkac</code> data structure,
which includes a public key and a challenge.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> cert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>).<span class="hljs-title class_">Certificate</span>();
<span class="hljs-keyword">const</span> spkac = <span class="hljs-title function_">getSpkacSomehow</span>();
<span class="hljs-keyword">const</span> publicKey = cert.<span class="hljs-title function_">exportPublicKey</span>(spkac);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(publicKey);
<span class="hljs-comment">// Prints: the public key as &#x3C;Buffer ...></span></code></pre>
<h5><code>certificate.verifySpkac(spkac)</code><span><a class="mark" href="#crypto_certificate_verifyspkac_spkac_1" id="crypto_certificate_verifyspkac_spkac_1">#</a></span></h5>
<div class="api_metadata">
<span>Added in: v0.11.8</span>
</div>
<ul>
<li><code>spkac</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> <code>true</code> if the given <code>spkac</code> data structure is valid,
<code>false</code> otherwise.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> cert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>).<span class="hljs-title class_">Certificate</span>();
<span class="hljs-keyword">const</span> spkac = <span class="hljs-title function_">getSpkacSomehow</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(cert.<span class="hljs-title function_">verifySpkac</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(spkac)));
<span class="hljs-comment">// Prints: true or false</span></code></pre>
</section><section><h3>Class: <code>Cipher</code><span><a class="mark" href="#crypto_class_cipher" id="crypto_class_cipher">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.94</span>
</div>
<ul>
<li>Extends: <a href="stream.html#stream_class_stream_transform" class="type">&#x3C;stream.Transform></a></li>
</ul>
<p>Instances of the <code>Cipher</code> class are used to encrypt data. The class can be
used in one of two ways:</p>
<ul>
<li>As a <a href="stream.html">stream</a> that is both readable and writable, where plain unencrypted
data is written to produce encrypted data on the readable side, or</li>
<li>Using the <a href="#crypto_cipher_update_data_inputencoding_outputencoding"><code>cipher.update()</code></a> and <a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a> methods to produce
the encrypted data.</li>
</ul>
<p>The <a href="#crypto_crypto_createcipher_algorithm_password_options"><code>crypto.createCipher()</code></a> or <a href="#crypto_crypto_createcipheriv_algorithm_key_iv_options"><code>crypto.createCipheriv()</code></a> methods are
used to create <code>Cipher</code> instances. <code>Cipher</code> objects are not to be created
directly using the <code>new</code> keyword.</p>
<p>Example: Using <code>Cipher</code> objects as streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> algorithm = <span class="hljs-string">'aes-192-cbc'</span>;
<span class="hljs-keyword">const</span> password = <span class="hljs-string">'Password used to generate key'</span>;
<span class="hljs-comment">// Key length is dependent on the algorithm. In this case for aes192, it is</span>
<span class="hljs-comment">// 24 bytes (192 bits).</span>
<span class="hljs-comment">// Use async `crypto.scrypt()` instead.</span>
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">scryptSync</span>(password, <span class="hljs-string">'salt'</span>, <span class="hljs-number">24</span>);
<span class="hljs-comment">// Use `crypto.randomBytes()` to generate a random iv instead of the static iv</span>
<span class="hljs-comment">// shown here.</span>
<span class="hljs-keyword">const</span> iv = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">16</span>, <span class="hljs-number">0</span>); <span class="hljs-comment">// Initialization vector.</span>

<span class="hljs-keyword">const</span> cipher = crypto.<span class="hljs-title function_">createCipheriv</span>(algorithm, key, iv);

<span class="hljs-keyword">let</span> encrypted = <span class="hljs-string">''</span>;
cipher.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-keyword">let</span> chunk;
  <span class="hljs-keyword">while</span> (<span class="hljs-literal">null</span> !== (chunk = cipher.<span class="hljs-title function_">read</span>())) {
    encrypted += chunk.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>);
  }
});
cipher.<span class="hljs-title function_">on</span>(<span class="hljs-string">'end'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(encrypted);
  <span class="hljs-comment">// Prints: e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa</span>
});

cipher.<span class="hljs-title function_">write</span>(<span class="hljs-string">'some clear text data'</span>);
cipher.<span class="hljs-title function_">end</span>();</code></pre>
<p>Example: Using <code>Cipher</code> and piped streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>);

<span class="hljs-keyword">const</span> algorithm = <span class="hljs-string">'aes-192-cbc'</span>;
<span class="hljs-keyword">const</span> password = <span class="hljs-string">'Password used to generate key'</span>;
<span class="hljs-comment">// Use the async `crypto.scrypt()` instead.</span>
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">scryptSync</span>(password, <span class="hljs-string">'salt'</span>, <span class="hljs-number">24</span>);
<span class="hljs-comment">// Use `crypto.randomBytes()` to generate a random iv instead of the static iv</span>
<span class="hljs-comment">// shown here.</span>
<span class="hljs-keyword">const</span> iv = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">16</span>, <span class="hljs-number">0</span>); <span class="hljs-comment">// Initialization vector.</span>

<span class="hljs-keyword">const</span> cipher = crypto.<span class="hljs-title function_">createCipheriv</span>(algorithm, key, iv);

<span class="hljs-keyword">const</span> input = fs.<span class="hljs-title function_">createReadStream</span>(<span class="hljs-string">'test.js'</span>);
<span class="hljs-keyword">const</span> output = fs.<span class="hljs-title function_">createWriteStream</span>(<span class="hljs-string">'test.enc'</span>);

input.<span class="hljs-title function_">pipe</span>(cipher).<span class="hljs-title function_">pipe</span>(output);</code></pre>
<p>Example: Using the <a href="#crypto_cipher_update_data_inputencoding_outputencoding"><code>cipher.update()</code></a> and <a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a> methods:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> algorithm = <span class="hljs-string">'aes-192-cbc'</span>;
<span class="hljs-keyword">const</span> password = <span class="hljs-string">'Password used to generate key'</span>;
<span class="hljs-comment">// Use the async `crypto.scrypt()` instead.</span>
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">scryptSync</span>(password, <span class="hljs-string">'salt'</span>, <span class="hljs-number">24</span>);
<span class="hljs-comment">// Use `crypto.randomBytes` to generate a random iv instead of the static iv</span>
<span class="hljs-comment">// shown here.</span>
<span class="hljs-keyword">const</span> iv = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">16</span>, <span class="hljs-number">0</span>); <span class="hljs-comment">// Initialization vector.</span>

<span class="hljs-keyword">const</span> cipher = crypto.<span class="hljs-title function_">createCipheriv</span>(algorithm, key, iv);

<span class="hljs-keyword">let</span> encrypted = cipher.<span class="hljs-title function_">update</span>(<span class="hljs-string">'some clear text data'</span>, <span class="hljs-string">'utf8'</span>, <span class="hljs-string">'hex'</span>);
encrypted += cipher.<span class="hljs-title function_">final</span>(<span class="hljs-string">'hex'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(encrypted);
<span class="hljs-comment">// Prints: e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa</span></code></pre>
<h4><code>cipher.final([outputEncoding])</code><span><a class="mark" href="#crypto_cipher_final_outputencoding" id="crypto_cipher_final_outputencoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.1.94</span>
</div>
<ul>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Any remaining enciphered contents.
If <code>outputEncoding</code> is specified, a string is
returned. If an <code>outputEncoding</code> is not provided, a <a href="buffer.html"><code>Buffer</code></a> is returned.</li>
</ul>
<p>Once the <code>cipher.final()</code> method has been called, the <code>Cipher</code> object can no
longer be used to encrypt data. Attempts to call <code>cipher.final()</code> more than
once will result in an error being thrown.</p>
<h4><code>cipher.getAuthTag()</code><span><a class="mark" href="#crypto_cipher_getauthtag" id="crypto_cipher_getauthtag">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v1.0.0</span>
</div>
<ul>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> When using an authenticated encryption mode (<code>GCM</code>, <code>CCM</code>
and <code>OCB</code> are currently supported), the <code>cipher.getAuthTag()</code> method returns a
<a href="buffer.html"><code>Buffer</code></a> containing the <em>authentication tag</em> that has been computed from
the given data.</li>
</ul>
<p>The <code>cipher.getAuthTag()</code> method should only be called after encryption has
been completed using the <a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a> method.</p>
<h4><code>cipher.setAAD(buffer[, options])</code><span><a class="mark" href="#crypto_cipher_setaad_buffer_options" id="crypto_cipher_setaad_buffer_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v1.0.0</span>
</div>
<ul>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a>
<ul>
<li><code>plaintextLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
</ul>
</li>
<li>Returns: <a href="crypto.html#crypto_class_cipher" class="type">&#x3C;Cipher></a> for method chaining.</li>
</ul>
<p>When using an authenticated encryption mode (<code>GCM</code>, <code>CCM</code> and <code>OCB</code> are
currently supported), the <code>cipher.setAAD()</code> method sets the value used for the
<em>additional authenticated data</em> (AAD) input parameter.</p>
<p>The <code>options</code> argument is optional for <code>GCM</code> and <code>OCB</code>. When using <code>CCM</code>, the
<code>plaintextLength</code> option must be specified and its value must match the length
of the plaintext in bytes. See <a href="#crypto_ccm_mode">CCM mode</a>.</p>
<p>The <code>cipher.setAAD()</code> method must be called before <a href="#crypto_cipher_update_data_inputencoding_outputencoding"><code>cipher.update()</code></a>.</p>
<h4><code>cipher.setAutoPadding([autoPadding])</code><span><a class="mark" href="#crypto_cipher_setautopadding_autopadding" id="crypto_cipher_setautopadding_autopadding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.7.1</span>
</div>
<ul>
<li><code>autoPadding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> <strong>Default:</strong> <code>true</code></li>
<li>Returns: <a href="crypto.html#crypto_class_cipher" class="type">&#x3C;Cipher></a> for method chaining.</li>
</ul>
<p>When using block encryption algorithms, the <code>Cipher</code> class will automatically
add padding to the input data to the appropriate block size. To disable the
default padding call <code>cipher.setAutoPadding(false)</code>.</p>
<p>When <code>autoPadding</code> is <code>false</code>, the length of the entire input data must be a
multiple of the cipher's block size or <a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a> will throw an error.
Disabling automatic padding is useful for non-standard padding, for instance
using <code>0x0</code> instead of PKCS padding.</p>
<p>The <code>cipher.setAutoPadding()</code> method must be called before
<a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a>.</p>
<h4><code>cipher.update(data[, inputEncoding][, outputEncoding])</code><span><a class="mark" href="#crypto_cipher_update_data_inputencoding_outputencoding" id="crypto_cipher_update_data_inputencoding_outputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the data.</li>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Updates the cipher with <code>data</code>. If the <code>inputEncoding</code> argument is given,
the <code>data</code>
argument is a string using the specified encoding. If the <code>inputEncoding</code>
argument is not given, <code>data</code> must be a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or
<code>DataView</code>. If <code>data</code> is a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or <code>DataView</code>, then
<code>inputEncoding</code> is ignored.</p>
<p>The <code>outputEncoding</code> specifies the output format of the enciphered
data. If the <code>outputEncoding</code>
is specified, a string using the specified encoding is returned. If no
<code>outputEncoding</code> is provided, a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<p>The <code>cipher.update()</code> method can be called multiple times with new data until
<a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a> is called. Calling <code>cipher.update()</code> after
<a href="#crypto_cipher_final_outputencoding"><code>cipher.final()</code></a> will result in an error being thrown.</p>
</section><section><h3>Class: <code>Decipher</code><span><a class="mark" href="#crypto_class_decipher" id="crypto_class_decipher">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.94</span>
</div>
<ul>
<li>Extends: <a href="stream.html#stream_class_stream_transform" class="type">&#x3C;stream.Transform></a></li>
</ul>
<p>Instances of the <code>Decipher</code> class are used to decrypt data. The class can be
used in one of two ways:</p>
<ul>
<li>As a <a href="stream.html">stream</a> that is both readable and writable, where plain encrypted
data is written to produce unencrypted data on the readable side, or</li>
<li>Using the <a href="#crypto_decipher_update_data_inputencoding_outputencoding"><code>decipher.update()</code></a> and <a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> methods to
produce the unencrypted data.</li>
</ul>
<p>The <a href="#crypto_crypto_createdecipher_algorithm_password_options"><code>crypto.createDecipher()</code></a> or <a href="#crypto_crypto_createdecipheriv_algorithm_key_iv_options"><code>crypto.createDecipheriv()</code></a> methods are
used to create <code>Decipher</code> instances. <code>Decipher</code> objects are not to be created
directly using the <code>new</code> keyword.</p>
<p>Example: Using <code>Decipher</code> objects as streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> algorithm = <span class="hljs-string">'aes-192-cbc'</span>;
<span class="hljs-keyword">const</span> password = <span class="hljs-string">'Password used to generate key'</span>;
<span class="hljs-comment">// Key length is dependent on the algorithm. In this case for aes192, it is</span>
<span class="hljs-comment">// 24 bytes (192 bits).</span>
<span class="hljs-comment">// Use the async `crypto.scrypt()` instead.</span>
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">scryptSync</span>(password, <span class="hljs-string">'salt'</span>, <span class="hljs-number">24</span>);
<span class="hljs-comment">// The IV is usually passed along with the ciphertext.</span>
<span class="hljs-keyword">const</span> iv = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">16</span>, <span class="hljs-number">0</span>); <span class="hljs-comment">// Initialization vector.</span>

<span class="hljs-keyword">const</span> decipher = crypto.<span class="hljs-title function_">createDecipheriv</span>(algorithm, key, iv);

<span class="hljs-keyword">let</span> decrypted = <span class="hljs-string">''</span>;
decipher.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-keyword">while</span> (<span class="hljs-literal">null</span> !== (chunk = decipher.<span class="hljs-title function_">read</span>())) {
    decrypted += chunk.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>);
  }
});
decipher.<span class="hljs-title function_">on</span>(<span class="hljs-string">'end'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(decrypted);
  <span class="hljs-comment">// Prints: some clear text data</span>
});

<span class="hljs-comment">// Encrypted with same algorithm, key and iv.</span>
<span class="hljs-keyword">const</span> encrypted =
  <span class="hljs-string">'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa'</span>;
decipher.<span class="hljs-title function_">write</span>(encrypted, <span class="hljs-string">'hex'</span>);
decipher.<span class="hljs-title function_">end</span>();</code></pre>
<p>Example: Using <code>Decipher</code> and piped streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>);

<span class="hljs-keyword">const</span> algorithm = <span class="hljs-string">'aes-192-cbc'</span>;
<span class="hljs-keyword">const</span> password = <span class="hljs-string">'Password used to generate key'</span>;
<span class="hljs-comment">// Use the async `crypto.scrypt()` instead.</span>
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">scryptSync</span>(password, <span class="hljs-string">'salt'</span>, <span class="hljs-number">24</span>);
<span class="hljs-comment">// The IV is usually passed along with the ciphertext.</span>
<span class="hljs-keyword">const</span> iv = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">16</span>, <span class="hljs-number">0</span>); <span class="hljs-comment">// Initialization vector.</span>

<span class="hljs-keyword">const</span> decipher = crypto.<span class="hljs-title function_">createDecipheriv</span>(algorithm, key, iv);

<span class="hljs-keyword">const</span> input = fs.<span class="hljs-title function_">createReadStream</span>(<span class="hljs-string">'test.enc'</span>);
<span class="hljs-keyword">const</span> output = fs.<span class="hljs-title function_">createWriteStream</span>(<span class="hljs-string">'test.js'</span>);

input.<span class="hljs-title function_">pipe</span>(decipher).<span class="hljs-title function_">pipe</span>(output);</code></pre>
<p>Example: Using the <a href="#crypto_decipher_update_data_inputencoding_outputencoding"><code>decipher.update()</code></a> and <a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> methods:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> algorithm = <span class="hljs-string">'aes-192-cbc'</span>;
<span class="hljs-keyword">const</span> password = <span class="hljs-string">'Password used to generate key'</span>;
<span class="hljs-comment">// Use the async `crypto.scrypt()` instead.</span>
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">scryptSync</span>(password, <span class="hljs-string">'salt'</span>, <span class="hljs-number">24</span>);
<span class="hljs-comment">// The IV is usually passed along with the ciphertext.</span>
<span class="hljs-keyword">const</span> iv = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">16</span>, <span class="hljs-number">0</span>); <span class="hljs-comment">// Initialization vector.</span>

<span class="hljs-keyword">const</span> decipher = crypto.<span class="hljs-title function_">createDecipheriv</span>(algorithm, key, iv);

<span class="hljs-comment">// Encrypted using same algorithm, key and iv.</span>
<span class="hljs-keyword">const</span> encrypted =
  <span class="hljs-string">'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa'</span>;
<span class="hljs-keyword">let</span> decrypted = decipher.<span class="hljs-title function_">update</span>(encrypted, <span class="hljs-string">'hex'</span>, <span class="hljs-string">'utf8'</span>);
decrypted += decipher.<span class="hljs-title function_">final</span>(<span class="hljs-string">'utf8'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(decrypted);
<span class="hljs-comment">// Prints: some clear text data</span></code></pre>
<h4><code>decipher.final([outputEncoding])</code><span><a class="mark" href="#crypto_decipher_final_outputencoding" id="crypto_decipher_final_outputencoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.1.94</span>
</div>
<ul>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Any remaining deciphered contents.
If <code>outputEncoding</code> is specified, a string is
returned. If an <code>outputEncoding</code> is not provided, a <a href="buffer.html"><code>Buffer</code></a> is returned.</li>
</ul>
<p>Once the <code>decipher.final()</code> method has been called, the <code>Decipher</code> object can
no longer be used to decrypt data. Attempts to call <code>decipher.final()</code> more
than once will result in an error being thrown.</p>
<h4><code>decipher.setAAD(buffer[, options])</code><span><a class="mark" href="#crypto_decipher_setaad_buffer_options" id="crypto_decipher_setaad_buffer_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v7.2.0</td>
<td><p>This method now returns a reference to <code>decipher</code>.</p></td></tr>
<tr><td>v1.0.0</td>
<td><p><span>Added in: v1.0.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a>
<ul>
<li><code>plaintextLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
</ul>
</li>
<li>Returns: <a href="crypto.html#crypto_class_decipher" class="type">&#x3C;Decipher></a> for method chaining.</li>
</ul>
<p>When using an authenticated encryption mode (<code>GCM</code>, <code>CCM</code> and <code>OCB</code> are
currently supported), the <code>decipher.setAAD()</code> method sets the value used for the
<em>additional authenticated data</em> (AAD) input parameter.</p>
<p>The <code>options</code> argument is optional for <code>GCM</code>. When using <code>CCM</code>, the
<code>plaintextLength</code> option must be specified and its value must match the length
of the ciphertext in bytes. See <a href="#crypto_ccm_mode">CCM mode</a>.</p>
<p>The <code>decipher.setAAD()</code> method must be called before <a href="#crypto_decipher_update_data_inputencoding_outputencoding"><code>decipher.update()</code></a>.</p>
<h4><code>decipher.setAuthTag(buffer)</code><span><a class="mark" href="#crypto_decipher_setauthtag_buffer" id="crypto_decipher_setauthtag_buffer">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.0.0</td>
<td><p>This method now throws if the GCM tag length is invalid.</p></td></tr>
<tr><td>v7.2.0</td>
<td><p>This method now returns a reference to <code>decipher</code>.</p></td></tr>
<tr><td>v1.0.0</td>
<td><p><span>Added in: v1.0.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="crypto.html#crypto_class_decipher" class="type">&#x3C;Decipher></a> for method chaining.</li>
</ul>
<p>When using an authenticated encryption mode (<code>GCM</code>, <code>CCM</code> and <code>OCB</code> are
currently supported), the <code>decipher.setAuthTag()</code> method is used to pass in the
received <em>authentication tag</em>. If no tag is provided, or if the cipher text
has been tampered with, <a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> will throw, indicating that the
cipher text should be discarded due to failed authentication. If the tag length
is invalid according to <a href="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf">NIST SP 800-38D</a> or does not match the value of the
<code>authTagLength</code> option, <code>decipher.setAuthTag()</code> will throw an error.</p>
<p>The <code>decipher.setAuthTag()</code> method must be called before <a href="#crypto_decipher_update_data_inputencoding_outputencoding"><code>decipher.update()</code></a>
for <code>CCM</code> mode or before <a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> for <code>GCM</code> and <code>OCB</code> modes.
<code>decipher.setAuthTag()</code> can only be called once.</p>
<h4><code>decipher.setAutoPadding([autoPadding])</code><span><a class="mark" href="#crypto_decipher_setautopadding_autopadding" id="crypto_decipher_setautopadding_autopadding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.7.1</span>
</div>
<ul>
<li><code>autoPadding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> <strong>Default:</strong> <code>true</code></li>
<li>Returns: <a href="crypto.html#crypto_class_decipher" class="type">&#x3C;Decipher></a> for method chaining.</li>
</ul>
<p>When data has been encrypted without standard block padding, calling
<code>decipher.setAutoPadding(false)</code> will disable automatic padding to prevent
<a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> from checking for and removing padding.</p>
<p>Turning auto padding off will only work if the input data's length is a
multiple of the ciphers block size.</p>
<p>The <code>decipher.setAutoPadding()</code> method must be called before
<a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a>.</p>
<h4><code>decipher.update(data[, inputEncoding][, outputEncoding])</code><span><a class="mark" href="#crypto_decipher_update_data_inputencoding_outputencoding" id="crypto_decipher_update_data_inputencoding_outputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>data</code> string.</li>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Updates the decipher with <code>data</code>. If the <code>inputEncoding</code> argument is given,
the <code>data</code>
argument is a string using the specified encoding. If the <code>inputEncoding</code>
argument is not given, <code>data</code> must be a <a href="buffer.html"><code>Buffer</code></a>. If <code>data</code> is a
<a href="buffer.html"><code>Buffer</code></a> then <code>inputEncoding</code> is ignored.</p>
<p>The <code>outputEncoding</code> specifies the output format of the enciphered
data. If the <code>outputEncoding</code>
is specified, a string using the specified encoding is returned. If no
<code>outputEncoding</code> is provided, a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<p>The <code>decipher.update()</code> method can be called multiple times with new data until
<a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> is called. Calling <code>decipher.update()</code> after
<a href="#crypto_decipher_final_outputencoding"><code>decipher.final()</code></a> will result in an error being thrown.</p>
</section><section><h3>Class: <code>DiffieHellman</code><span><a class="mark" href="#crypto_class_diffiehellman" id="crypto_class_diffiehellman">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<p>The <code>DiffieHellman</code> class is a utility for creating Diffie-Hellman key
exchanges.</p>
<p>Instances of the <code>DiffieHellman</code> class can be created using the
<a href="#crypto_crypto_creatediffiehellman_prime_primeencoding_generator_generatorencoding"><code>crypto.createDiffieHellman()</code></a> function.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'assert'</span>);

<span class="hljs-comment">// Generate Alice's keys...</span>
<span class="hljs-keyword">const</span> alice = crypto.<span class="hljs-title function_">createDiffieHellman</span>(<span class="hljs-number">2048</span>);
<span class="hljs-keyword">const</span> aliceKey = alice.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-comment">// Generate Bob's keys...</span>
<span class="hljs-keyword">const</span> bob = crypto.<span class="hljs-title function_">createDiffieHellman</span>(alice.<span class="hljs-title function_">getPrime</span>(), alice.<span class="hljs-title function_">getGenerator</span>());
<span class="hljs-keyword">const</span> bobKey = bob.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-comment">// Exchange and generate the secret...</span>
<span class="hljs-keyword">const</span> aliceSecret = alice.<span class="hljs-title function_">computeSecret</span>(bobKey);
<span class="hljs-keyword">const</span> bobSecret = bob.<span class="hljs-title function_">computeSecret</span>(aliceKey);

<span class="hljs-comment">// OK</span>
assert.<span class="hljs-title function_">strictEqual</span>(aliceSecret.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>), bobSecret.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));</code></pre>
<h4><code>diffieHellman.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])</code><span><a class="mark" href="#crypto_diffiehellman_computesecret_otherpublickey_inputencoding_outputencoding" id="crypto_diffiehellman_computesecret_otherpublickey_inputencoding_outputencoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>otherPublicKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of an <code>otherPublicKey</code> string.</li>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Computes the shared secret using <code>otherPublicKey</code> as the other
party's public key and returns the computed shared secret. The supplied
key is interpreted using the specified <code>inputEncoding</code>, and secret is
encoded using specified <code>outputEncoding</code>.
If the <code>inputEncoding</code> is not
provided, <code>otherPublicKey</code> is expected to be a <a href="buffer.html"><code>Buffer</code></a>,
<code>TypedArray</code>, or <code>DataView</code>.</p>
<p>If <code>outputEncoding</code> is given a string is returned; otherwise, a
<a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<h4><code>diffieHellman.generateKeys([encoding])</code><span><a class="mark" href="#crypto_diffiehellman_generatekeys_encoding" id="crypto_diffiehellman_generatekeys_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Generates private and public Diffie-Hellman key values, and returns
the public key in the specified <code>encoding</code>. This key should be
transferred to the other party.
If <code>encoding</code> is provided a string is returned; otherwise a
<a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<h4><code>diffieHellman.getGenerator([encoding])</code><span><a class="mark" href="#crypto_diffiehellman_getgenerator_encoding" id="crypto_diffiehellman_getgenerator_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Returns the Diffie-Hellman generator in the specified <code>encoding</code>.
If <code>encoding</code> is provided a string is
returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<h4><code>diffieHellman.getPrime([encoding])</code><span><a class="mark" href="#crypto_diffiehellman_getprime_encoding" id="crypto_diffiehellman_getprime_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Returns the Diffie-Hellman prime in the specified <code>encoding</code>.
If <code>encoding</code> is provided a string is
returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<h4><code>diffieHellman.getPrivateKey([encoding])</code><span><a class="mark" href="#crypto_diffiehellman_getprivatekey_encoding" id="crypto_diffiehellman_getprivatekey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Returns the Diffie-Hellman private key in the specified <code>encoding</code>.
If <code>encoding</code> is provided a
string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<h4><code>diffieHellman.getPublicKey([encoding])</code><span><a class="mark" href="#crypto_diffiehellman_getpublickey_encoding" id="crypto_diffiehellman_getpublickey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Returns the Diffie-Hellman public key in the specified <code>encoding</code>.
If <code>encoding</code> is provided a
string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<h4><code>diffieHellman.setPrivateKey(privateKey[, encoding])</code><span><a class="mark" href="#crypto_diffiehellman_setprivatekey_privatekey_encoding" id="crypto_diffiehellman_setprivatekey_privatekey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>privateKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>privateKey</code> string.</li>
</ul>
<p>Sets the Diffie-Hellman private key. If the <code>encoding</code> argument is provided,
<code>privateKey</code> is expected
to be a string. If no <code>encoding</code> is provided, <code>privateKey</code> is expected
to be a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or <code>DataView</code>.</p>
<h4><code>diffieHellman.setPublicKey(publicKey[, encoding])</code><span><a class="mark" href="#crypto_diffiehellman_setpublickey_publickey_encoding" id="crypto_diffiehellman_setpublickey_publickey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>publicKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>publicKey</code> string.</li>
</ul>
<p>Sets the Diffie-Hellman public key. If the <code>encoding</code> argument is provided,
<code>publicKey</code> is expected
to be a string. If no <code>encoding</code> is provided, <code>publicKey</code> is expected
to be a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or <code>DataView</code>.</p>
<h4><code>diffieHellman.verifyError</code><span><a class="mark" href="#crypto_diffiehellman_verifyerror" id="crypto_diffiehellman_verifyerror">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.12</span>
</div>
<p>A bit field containing any warnings and/or errors resulting from a check
performed during initialization of the <code>DiffieHellman</code> object.</p>
<p>The following values are valid for this property (as defined in <code>constants</code>
module):</p>
<ul>
<li><code>DH_CHECK_P_NOT_SAFE_PRIME</code></li>
<li><code>DH_CHECK_P_NOT_PRIME</code></li>
<li><code>DH_UNABLE_TO_CHECK_GENERATOR</code></li>
<li><code>DH_NOT_SUITABLE_GENERATOR</code></li>
</ul>
</section><section><h3>Class: <code>DiffieHellmanGroup</code><span><a class="mark" href="#crypto_class_diffiehellmangroup" id="crypto_class_diffiehellmangroup">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.7.5</span>
</div>
<p>The <code>DiffieHellmanGroup</code> class takes a well-known modp group as its argument.
It works the same as <code>DiffieHellman</code>, except that it does not allow changing
its keys after creation. In other words, it does not implement <code>setPublicKey()</code>
or <code>setPrivateKey()</code> methods.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> name = <span class="hljs-string">'modp1'</span>;
<span class="hljs-keyword">const</span> dh = crypto.<span class="hljs-title function_">createDiffieHellmanGroup</span>(name);</code></pre>
<p><code>name</code> is taken from <a href="https://www.rfc-editor.org/rfc/rfc2412.txt">RFC 2412</a> (modp1 and 2) and <a href="https://www.rfc-editor.org/rfc/rfc3526.txt">RFC 3526</a>:</p>
<pre><code class="language-console"><span class="hljs-meta">$ </span><span class="language-bash">perl -ne <span class="hljs-string">'print "$1\n" if /"(modp\d+)"/'</span> src/node_crypto_groups.h</span>
modp1  #  768 bits
modp2  # 1024 bits
modp5  # 1536 bits
modp14 # 2048 bits
modp15 # etc.
modp16
modp17
modp18</code></pre>
</section><section><h3>Class: <code>ECDH</code><span><a class="mark" href="#crypto_class_ecdh" id="crypto_class_ecdh">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.11.14</span>
</div>
<p>The <code>ECDH</code> class is a utility for creating Elliptic Curve Diffie-Hellman (ECDH)
key exchanges.</p>
<p>Instances of the <code>ECDH</code> class can be created using the
<a href="#crypto_crypto_createecdh_curvename"><code>crypto.createECDH()</code></a> function.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'assert'</span>);

<span class="hljs-comment">// Generate Alice's keys...</span>
<span class="hljs-keyword">const</span> alice = crypto.<span class="hljs-title function_">createECDH</span>(<span class="hljs-string">'secp521r1'</span>);
<span class="hljs-keyword">const</span> aliceKey = alice.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-comment">// Generate Bob's keys...</span>
<span class="hljs-keyword">const</span> bob = crypto.<span class="hljs-title function_">createECDH</span>(<span class="hljs-string">'secp521r1'</span>);
<span class="hljs-keyword">const</span> bobKey = bob.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-comment">// Exchange and generate the secret...</span>
<span class="hljs-keyword">const</span> aliceSecret = alice.<span class="hljs-title function_">computeSecret</span>(bobKey);
<span class="hljs-keyword">const</span> bobSecret = bob.<span class="hljs-title function_">computeSecret</span>(aliceKey);

assert.<span class="hljs-title function_">strictEqual</span>(aliceSecret.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>), bobSecret.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
<span class="hljs-comment">// OK</span></code></pre>
<h4>Static method: <code>ECDH.convertKey(key, curve[, inputEncoding[, outputEncoding[, format]]])</code><span><a class="mark" href="#crypto_static_method_ecdh_convertkey_key_curve_inputencoding_outputencoding_format" id="crypto_static_method_ecdh_convertkey_key_curve_inputencoding_outputencoding_format">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v10.0.0</span>
</div>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>curve</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>key</code> string.</li>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li><code>format</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> <strong>Default:</strong> <code>'uncompressed'</code></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Converts the EC Diffie-Hellman public key specified by <code>key</code> and <code>curve</code> to the
format specified by <code>format</code>. The <code>format</code> argument specifies point encoding
and can be <code>'compressed'</code>, <code>'uncompressed'</code> or <code>'hybrid'</code>. The supplied key is
interpreted using the specified <code>inputEncoding</code>, and the returned key is encoded
using the specified <code>outputEncoding</code>.</p>
<p>Use <a href="#crypto_crypto_getcurves"><code>crypto.getCurves()</code></a> to obtain a list of available curve names.
On recent OpenSSL releases, <code>openssl ecparam -list_curves</code> will also display
the name and description of each available elliptic curve.</p>
<p>If <code>format</code> is not specified the point will be returned in <code>'uncompressed'</code>
format.</p>
<p>If the <code>inputEncoding</code> is not provided, <code>key</code> is expected to be a <a href="buffer.html"><code>Buffer</code></a>,
<code>TypedArray</code>, or <code>DataView</code>.</p>
<p>Example (uncompressing a key):</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { createECDH, <span class="hljs-variable constant_">ECDH</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> ecdh = <span class="hljs-title function_">createECDH</span>(<span class="hljs-string">'secp256k1'</span>);
ecdh.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-keyword">const</span> compressedKey = ecdh.<span class="hljs-title function_">getPublicKey</span>(<span class="hljs-string">'hex'</span>, <span class="hljs-string">'compressed'</span>);

<span class="hljs-keyword">const</span> uncompressedKey = <span class="hljs-variable constant_">ECDH</span>.<span class="hljs-title function_">convertKey</span>(compressedKey,
                                        <span class="hljs-string">'secp256k1'</span>,
                                        <span class="hljs-string">'hex'</span>,
                                        <span class="hljs-string">'hex'</span>,
                                        <span class="hljs-string">'uncompressed'</span>);

<span class="hljs-comment">// The converted key and the uncompressed public key should be the same</span>
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(uncompressedKey === ecdh.<span class="hljs-title function_">getPublicKey</span>(<span class="hljs-string">'hex'</span>));</code></pre>
<h4><code>ecdh.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])</code><span><a class="mark" href="#crypto_ecdh_computesecret_otherpublickey_inputencoding_outputencoding" id="crypto_ecdh_computesecret_otherpublickey_inputencoding_outputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>Changed error format to better support invalid public key error.</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.11.14</td>
<td><p><span>Added in: v0.11.14</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>otherPublicKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>otherPublicKey</code> string.</li>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Computes the shared secret using <code>otherPublicKey</code> as the other
party's public key and returns the computed shared secret. The supplied
key is interpreted using specified <code>inputEncoding</code>, and the returned secret
is encoded using the specified <code>outputEncoding</code>.
If the <code>inputEncoding</code> is not
provided, <code>otherPublicKey</code> is expected to be a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or
<code>DataView</code>.</p>
<p>If <code>outputEncoding</code> is given a string will be returned; otherwise a
<a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<p><code>ecdh.computeSecret</code> will throw an
<code>ERR_CRYPTO_ECDH_INVALID_PUBLIC_KEY</code> error when <code>otherPublicKey</code>
lies outside of the elliptic curve. Since <code>otherPublicKey</code> is
usually supplied from a remote user over an insecure network,
be sure to handle this exception accordingly.</p>
<h4><code>ecdh.generateKeys([encoding[, format]])</code><span><a class="mark" href="#crypto_ecdh_generatekeys_encoding_format" id="crypto_ecdh_generatekeys_encoding_format">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.14</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li><code>format</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> <strong>Default:</strong> <code>'uncompressed'</code></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Generates private and public EC Diffie-Hellman key values, and returns
the public key in the specified <code>format</code> and <code>encoding</code>. This key should be
transferred to the other party.</p>
<p>The <code>format</code> argument specifies point encoding and can be <code>'compressed'</code> or
<code>'uncompressed'</code>. If <code>format</code> is not specified, the point will be returned in
<code>'uncompressed'</code> format.</p>
<p>If <code>encoding</code> is provided a string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a>
is returned.</p>
<h4><code>ecdh.getPrivateKey([encoding])</code><span><a class="mark" href="#crypto_ecdh_getprivatekey_encoding" id="crypto_ecdh_getprivatekey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.14</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The EC Diffie-Hellman in the specified <code>encoding</code>.</li>
</ul>
<p>If <code>encoding</code> is specified, a string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is
returned.</p>
<h4><code>ecdh.getPublicKey([encoding][, format])</code><span><a class="mark" href="#crypto_ecdh_getpublickey_encoding_format" id="crypto_ecdh_getpublickey_encoding_format">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.14</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li><code>format</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> <strong>Default:</strong> <code>'uncompressed'</code></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The EC Diffie-Hellman public key in the specified
<code>encoding</code> and <code>format</code>.</li>
</ul>
<p>The <code>format</code> argument specifies point encoding and can be <code>'compressed'</code> or
<code>'uncompressed'</code>. If <code>format</code> is not specified the point will be returned in
<code>'uncompressed'</code> format.</p>
<p>If <code>encoding</code> is specified, a string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is
returned.</p>
<h4><code>ecdh.setPrivateKey(privateKey[, encoding])</code><span><a class="mark" href="#crypto_ecdh_setprivatekey_privatekey_encoding" id="crypto_ecdh_setprivatekey_privatekey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.14</span>
</div>
<ul>
<li><code>privateKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>privateKey</code> string.</li>
</ul>
<p>Sets the EC Diffie-Hellman private key.
If <code>encoding</code> is provided, <code>privateKey</code> is expected
to be a string; otherwise <code>privateKey</code> is expected to be a <a href="buffer.html"><code>Buffer</code></a>,
<code>TypedArray</code>, or <code>DataView</code>.</p>
<p>If <code>privateKey</code> is not valid for the curve specified when the <code>ECDH</code> object was
created, an error is thrown. Upon setting the private key, the associated
public point (key) is also generated and set in the <code>ECDH</code> object.</p>
<h4><code>ecdh.setPublicKey(publicKey[, encoding])</code><span><a class="mark" href="#crypto_ecdh_setpublickey_publickey_encoding" id="crypto_ecdh_setpublickey_publickey_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.14</span><span>Deprecated since: v5.2.0</span>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated</div><p></p>
<ul>
<li><code>publicKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>publicKey</code> string.</li>
</ul>
<p>Sets the EC Diffie-Hellman public key.
If <code>encoding</code> is provided <code>publicKey</code> is expected to
be a string; otherwise a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or <code>DataView</code> is expected.</p>
<p>There is not normally a reason to call this method because <code>ECDH</code>
only requires a private key and the other party's public key to compute the
shared secret. Typically either <a href="#crypto_ecdh_generatekeys_encoding_format"><code>ecdh.generateKeys()</code></a> or
<a href="#crypto_ecdh_setprivatekey_privatekey_encoding"><code>ecdh.setPrivateKey()</code></a> will be called. The <a href="#crypto_ecdh_setprivatekey_privatekey_encoding"><code>ecdh.setPrivateKey()</code></a> method
attempts to generate the public point/key associated with the private key being
set.</p>
<p>Example (obtaining a shared secret):</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> alice = crypto.<span class="hljs-title function_">createECDH</span>(<span class="hljs-string">'secp256k1'</span>);
<span class="hljs-keyword">const</span> bob = crypto.<span class="hljs-title function_">createECDH</span>(<span class="hljs-string">'secp256k1'</span>);

<span class="hljs-comment">// This is a shortcut way of specifying one of Alice's previous private</span>
<span class="hljs-comment">// keys. It would be unwise to use such a predictable private key in a real</span>
<span class="hljs-comment">// application.</span>
alice.<span class="hljs-title function_">setPrivateKey</span>(
  crypto.<span class="hljs-title function_">createHash</span>(<span class="hljs-string">'sha256'</span>).<span class="hljs-title function_">update</span>(<span class="hljs-string">'alice'</span>, <span class="hljs-string">'utf8'</span>).<span class="hljs-title function_">digest</span>()
);

<span class="hljs-comment">// Bob uses a newly generated cryptographically strong</span>
<span class="hljs-comment">// pseudorandom key pair</span>
bob.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-keyword">const</span> aliceSecret = alice.<span class="hljs-title function_">computeSecret</span>(bob.<span class="hljs-title function_">getPublicKey</span>(), <span class="hljs-literal">null</span>, <span class="hljs-string">'hex'</span>);
<span class="hljs-keyword">const</span> bobSecret = bob.<span class="hljs-title function_">computeSecret</span>(alice.<span class="hljs-title function_">getPublicKey</span>(), <span class="hljs-literal">null</span>, <span class="hljs-string">'hex'</span>);

<span class="hljs-comment">// aliceSecret and bobSecret should be the same shared secret value</span>
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(aliceSecret === bobSecret);</code></pre>
</section><section><h3>Class: <code>Hash</code><span><a class="mark" href="#crypto_class_hash" id="crypto_class_hash">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.92</span>
</div>
<ul>
<li>Extends: <a href="stream.html#stream_class_stream_transform" class="type">&#x3C;stream.Transform></a></li>
</ul>
<p>The <code>Hash</code> class is a utility for creating hash digests of data. It can be
used in one of two ways:</p>
<ul>
<li>As a <a href="stream.html">stream</a> that is both readable and writable, where data is written
to produce a computed hash digest on the readable side, or</li>
<li>Using the <a href="#crypto_hash_update_data_inputencoding"><code>hash.update()</code></a> and <a href="#crypto_hash_digest_encoding"><code>hash.digest()</code></a> methods to produce the
computed hash.</li>
</ul>
<p>The <a href="#crypto_crypto_createhash_algorithm_options"><code>crypto.createHash()</code></a> method is used to create <code>Hash</code> instances. <code>Hash</code>
objects are not to be created directly using the <code>new</code> keyword.</p>
<p>Example: Using <code>Hash</code> objects as streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> hash = crypto.<span class="hljs-title function_">createHash</span>(<span class="hljs-string">'sha256'</span>);

hash.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-comment">// Only one element is going to be produced by the</span>
  <span class="hljs-comment">// hash stream.</span>
  <span class="hljs-keyword">const</span> data = hash.<span class="hljs-title function_">read</span>();
  <span class="hljs-keyword">if</span> (data) {
    <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(data.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
    <span class="hljs-comment">// Prints:</span>
    <span class="hljs-comment">//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50</span>
  }
});

hash.<span class="hljs-title function_">write</span>(<span class="hljs-string">'some data to hash'</span>);
hash.<span class="hljs-title function_">end</span>();</code></pre>
<p>Example: Using <code>Hash</code> and piped streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>);
<span class="hljs-keyword">const</span> hash = crypto.<span class="hljs-title function_">createHash</span>(<span class="hljs-string">'sha256'</span>);

<span class="hljs-keyword">const</span> input = fs.<span class="hljs-title function_">createReadStream</span>(<span class="hljs-string">'test.js'</span>);
input.<span class="hljs-title function_">pipe</span>(hash).<span class="hljs-title function_">setEncoding</span>(<span class="hljs-string">'hex'</span>).<span class="hljs-title function_">pipe</span>(process.<span class="hljs-property">stdout</span>);</code></pre>
<p>Example: Using the <a href="#crypto_hash_update_data_inputencoding"><code>hash.update()</code></a> and <a href="#crypto_hash_digest_encoding"><code>hash.digest()</code></a> methods:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> hash = crypto.<span class="hljs-title function_">createHash</span>(<span class="hljs-string">'sha256'</span>);

hash.<span class="hljs-title function_">update</span>(<span class="hljs-string">'some data to hash'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hash.<span class="hljs-title function_">digest</span>(<span class="hljs-string">'hex'</span>));
<span class="hljs-comment">// Prints:</span>
<span class="hljs-comment">//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50</span></code></pre>
<h4><code>hash.copy([options])</code><span><a class="mark" href="#crypto_hash_copy_options" id="crypto_hash_copy_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v13.1.0</span>
</div>
<ul>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_hash" class="type">&#x3C;Hash></a></li>
</ul>
<p>Creates a new <code>Hash</code> object that contains a deep copy of the internal state
of the current <code>Hash</code> object.</p>
<p>The optional <code>options</code> argument controls stream behavior. For XOF hash
functions such as <code>'shake256'</code>, the <code>outputLength</code> option can be used to
specify the desired output length in bytes.</p>
<p>An error is thrown when an attempt is made to copy the <code>Hash</code> object after
its <a href="#crypto_hash_digest_encoding"><code>hash.digest()</code></a> method has been called.</p>
<pre><code class="language-js"><span class="hljs-comment">// Calculate a rolling hash.</span>
<span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> hash = crypto.<span class="hljs-title function_">createHash</span>(<span class="hljs-string">'sha256'</span>);

hash.<span class="hljs-title function_">update</span>(<span class="hljs-string">'one'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hash.<span class="hljs-title function_">copy</span>().<span class="hljs-title function_">digest</span>(<span class="hljs-string">'hex'</span>));

hash.<span class="hljs-title function_">update</span>(<span class="hljs-string">'two'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hash.<span class="hljs-title function_">copy</span>().<span class="hljs-title function_">digest</span>(<span class="hljs-string">'hex'</span>));

hash.<span class="hljs-title function_">update</span>(<span class="hljs-string">'three'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hash.<span class="hljs-title function_">copy</span>().<span class="hljs-title function_">digest</span>(<span class="hljs-string">'hex'</span>));

<span class="hljs-comment">// Etc.</span></code></pre>
<h4><code>hash.digest([encoding])</code><span><a class="mark" href="#crypto_hash_digest_encoding" id="crypto_hash_digest_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.1.92</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Calculates the digest of all of the data passed to be hashed (using the
<a href="#crypto_hash_update_data_inputencoding"><code>hash.update()</code></a> method).
If <code>encoding</code> is provided a string will be returned; otherwise
a <a href="buffer.html"><code>Buffer</code></a> is returned.</p>
<p>The <code>Hash</code> object can not be used again after <code>hash.digest()</code> method has been
called. Multiple calls will cause an error to be thrown.</p>
<h4><code>hash.update(data[, inputEncoding])</code><span><a class="mark" href="#crypto_hash_update_data_inputencoding" id="crypto_hash_update_data_inputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.1.92</td>
<td><p><span>Added in: v0.1.92</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>data</code> string.</li>
</ul>
<p>Updates the hash content with the given <code>data</code>, the encoding of which
is given in <code>inputEncoding</code>.
If <code>encoding</code> is not provided, and the <code>data</code> is a string, an
encoding of <code>'utf8'</code> is enforced. If <code>data</code> is a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or
<code>DataView</code>, then <code>inputEncoding</code> is ignored.</p>
<p>This can be called many times with new data as it is streamed.</p>
</section><section><h3>Class: <code>Hmac</code><span><a class="mark" href="#crypto_class_hmac" id="crypto_class_hmac">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.94</span>
</div>
<ul>
<li>Extends: <a href="stream.html#stream_class_stream_transform" class="type">&#x3C;stream.Transform></a></li>
</ul>
<p>The <code>Hmac</code> class is a utility for creating cryptographic HMAC digests. It can
be used in one of two ways:</p>
<ul>
<li>As a <a href="stream.html">stream</a> that is both readable and writable, where data is written
to produce a computed HMAC digest on the readable side, or</li>
<li>Using the <a href="#crypto_hmac_update_data_inputencoding"><code>hmac.update()</code></a> and <a href="#crypto_hmac_digest_encoding"><code>hmac.digest()</code></a> methods to produce the
computed HMAC digest.</li>
</ul>
<p>The <a href="#crypto_crypto_createhmac_algorithm_key_options"><code>crypto.createHmac()</code></a> method is used to create <code>Hmac</code> instances. <code>Hmac</code>
objects are not to be created directly using the <code>new</code> keyword.</p>
<p>Example: Using <code>Hmac</code> objects as streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> hmac = crypto.<span class="hljs-title function_">createHmac</span>(<span class="hljs-string">'sha256'</span>, <span class="hljs-string">'a secret'</span>);

hmac.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-comment">// Only one element is going to be produced by the</span>
  <span class="hljs-comment">// hash stream.</span>
  <span class="hljs-keyword">const</span> data = hmac.<span class="hljs-title function_">read</span>();
  <span class="hljs-keyword">if</span> (data) {
    <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(data.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
    <span class="hljs-comment">// Prints:</span>
    <span class="hljs-comment">//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e</span>
  }
});

hmac.<span class="hljs-title function_">write</span>(<span class="hljs-string">'some data to hash'</span>);
hmac.<span class="hljs-title function_">end</span>();</code></pre>
<p>Example: Using <code>Hmac</code> and piped streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>);
<span class="hljs-keyword">const</span> hmac = crypto.<span class="hljs-title function_">createHmac</span>(<span class="hljs-string">'sha256'</span>, <span class="hljs-string">'a secret'</span>);

<span class="hljs-keyword">const</span> input = fs.<span class="hljs-title function_">createReadStream</span>(<span class="hljs-string">'test.js'</span>);
input.<span class="hljs-title function_">pipe</span>(hmac).<span class="hljs-title function_">pipe</span>(process.<span class="hljs-property">stdout</span>);</code></pre>
<p>Example: Using the <a href="#crypto_hmac_update_data_inputencoding"><code>hmac.update()</code></a> and <a href="#crypto_hmac_digest_encoding"><code>hmac.digest()</code></a> methods:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> hmac = crypto.<span class="hljs-title function_">createHmac</span>(<span class="hljs-string">'sha256'</span>, <span class="hljs-string">'a secret'</span>);

hmac.<span class="hljs-title function_">update</span>(<span class="hljs-string">'some data to hash'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hmac.<span class="hljs-title function_">digest</span>(<span class="hljs-string">'hex'</span>));
<span class="hljs-comment">// Prints:</span>
<span class="hljs-comment">//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e</span></code></pre>
<h4><code>hmac.digest([encoding])</code><span><a class="mark" href="#crypto_hmac_digest_encoding" id="crypto_hmac_digest_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.1.94</span>
</div>
<ul>
<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Calculates the HMAC digest of all of the data passed using <a href="#crypto_hmac_update_data_inputencoding"><code>hmac.update()</code></a>.
If <code>encoding</code> is
provided a string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a> is returned;</p>
<p>The <code>Hmac</code> object can not be used again after <code>hmac.digest()</code> has been
called. Multiple calls to <code>hmac.digest()</code> will result in an error being thrown.</p>
<h4><code>hmac.update(data[, inputEncoding])</code><span><a class="mark" href="#crypto_hmac_update_data_inputencoding" id="crypto_hmac_update_data_inputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>data</code> string.</li>
</ul>
<p>Updates the <code>Hmac</code> content with the given <code>data</code>, the encoding of which
is given in <code>inputEncoding</code>.
If <code>encoding</code> is not provided, and the <code>data</code> is a string, an
encoding of <code>'utf8'</code> is enforced. If <code>data</code> is a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or
<code>DataView</code>, then <code>inputEncoding</code> is ignored.</p>
<p>This can be called many times with new data as it is streamed.</p>
</section><section><h3>Class: <code>KeyObject</code><span><a class="mark" href="#crypto_class_keyobject" id="crypto_class_keyobject">#</a></span></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v14.5.0</td>
<td><p>Instances of this class can now be passed to worker threads using <code>postMessage</code>.</p></td></tr>
<tr><td>v11.13.0</td>
<td><p>This class is now exported.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p><span>Added in: v11.6.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<p>Node.js uses a <code>KeyObject</code> class to represent a symmetric or asymmetric key,
and each kind of key exposes different functions. The
<a href="#crypto_crypto_createsecretkey_key"><code>crypto.createSecretKey()</code></a>, <a href="#crypto_crypto_createpublickey_key"><code>crypto.createPublicKey()</code></a> and
<a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey()</code></a> methods are used to create <code>KeyObject</code>
instances. <code>KeyObject</code> objects are not to be created directly using the <code>new</code>
keyword.</p>
<p>Most applications should consider using the new <code>KeyObject</code> API instead of
passing keys as strings or <code>Buffer</code>s due to improved security features.</p>
<p><code>KeyObject</code> instances can be passed to other threads via <a href="worker_threads.html#worker_threads_port_postmessage_value_transferlist"><code>postMessage()</code></a>.
The receiver obtains a cloned <code>KeyObject</code>, and the <code>KeyObject</code> does not need to
be listed in the <code>transferList</code> argument.</p>
<h4><code>keyObject.asymmetricKeyType</code><span><a class="mark" href="#crypto_keyobject_asymmetrickeytype" id="crypto_keyobject_asymmetrickeytype">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.9.0</td>
<td><p>Added support for <code>'dh'</code>.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>Added support for <code>'rsa-pss'</code>.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>This property now returns <code>undefined</code> for KeyObject instances of unrecognized type instead of aborting.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>Added support for <code>'x25519'</code> and <code>'x448'</code>.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>Added support for <code>'ed25519'</code> and <code>'ed448'</code>.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p><span>Added in: v11.6.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>For asymmetric keys, this property represents the type of the key. Supported key
types are:</p>
<ul>
<li><code>'rsa'</code> (OID 1.2.840.113549.1.1.1)</li>
<li><code>'rsa-pss'</code> (OID 1.2.840.113549.1.1.10)</li>
<li><code>'dsa'</code> (OID 1.2.840.10040.4.1)</li>
<li><code>'ec'</code> (OID 1.2.840.10045.2.1)</li>
<li><code>'x25519'</code> (OID 1.3.101.110)</li>
<li><code>'x448'</code> (OID 1.3.101.111)</li>
<li><code>'ed25519'</code> (OID 1.3.101.112)</li>
<li><code>'ed448'</code> (OID 1.3.101.113)</li>
<li><code>'dh'</code> (OID 1.2.840.113549.1.3.1)</li>
</ul>
<p>This property is <code>undefined</code> for unrecognized <code>KeyObject</code> types and symmetric
keys.</p>
<h4><code>keyObject.export([options])</code><span><a class="mark" href="#crypto_keyobject_export_options" id="crypto_keyobject_export_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v11.6.0</span>
</div>
<ul>
<li><code>options</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
<p>For symmetric keys, this function allocates a <code>Buffer</code> containing the key
material and ignores any options.</p>
<p>For asymmetric keys, the <code>options</code> parameter is used to determine the export
format.</p>
<p>For public keys, the following encoding options can be used:</p>
<ul>
<li><code>type</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be one of <code>'pkcs1'</code> (RSA only) or <code>'spki'</code>.</li>
<li><code>format</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'pem'</code> or <code>'der'</code>.</li>
</ul>
<p>For private keys, the following encoding options can be used:</p>
<ul>
<li><code>type</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be one of <code>'pkcs1'</code> (RSA only), <code>'pkcs8'</code> or
<code>'sec1'</code> (EC only).</li>
<li><code>format</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'pem'</code> or <code>'der'</code>.</li>
<li><code>cipher</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> If specified, the private key will be encrypted with
the given <code>cipher</code> and <code>passphrase</code> using PKCS#5 v2.0 password based
encryption.</li>
<li><code>passphrase</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The passphrase to use for encryption, see
<code>cipher</code>.</li>
</ul>
<p>When PEM encoding was selected, the result will be a string, otherwise it will
be a buffer containing the data encoded as DER.</p>
<p>PKCS#1, SEC1, and PKCS#8 type keys can be encrypted by using a combination of
the <code>cipher</code> and <code>format</code> options. The PKCS#8 <code>type</code> can be used with any
<code>format</code> to encrypt any key algorithm (RSA, EC, or DH) by specifying a
<code>cipher</code>. PKCS#1 and SEC1 can only be encrypted by specifying a <code>cipher</code>
when the PEM <code>format</code> is used. For maximum compatibility, use PKCS#8 for
encrypted private keys. Since PKCS#8 defines its own
encryption mechanism, PEM-level encryption is not supported when encrypting
a PKCS#8 key. See <a href="https://www.rfc-editor.org/rfc/rfc5208.txt">RFC 5208</a> for PKCS#8 encryption and <a href="https://www.rfc-editor.org/rfc/rfc1421.txt">RFC 1421</a> for
PKCS#1 and SEC1 encryption.</p>
<h4><code>keyObject.symmetricKeySize</code><span><a class="mark" href="#crypto_keyobject_symmetrickeysize" id="crypto_keyobject_symmetrickeysize">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v11.6.0</span>
</div>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
</ul>
<p>For secret keys, this property represents the size of the key in bytes. This
property is <code>undefined</code> for asymmetric keys.</p>
<h4><code>keyObject.type</code><span><a class="mark" href="#crypto_keyobject_type" id="crypto_keyobject_type">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v11.6.0</span>
</div>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Depending on the type of this <code>KeyObject</code>, this property is either
<code>'secret'</code> for secret (symmetric) keys, <code>'public'</code> for public (asymmetric) keys
or <code>'private'</code> for private (asymmetric) keys.</p>
</section><section><h3>Class: <code>Sign</code><span><a class="mark" href="#crypto_class_sign" id="crypto_class_sign">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.92</span>
</div>
<ul>
<li>Extends: <a href="stream.html#stream_class_stream_writable" class="type">&#x3C;stream.Writable></a></li>
</ul>
<p>The <code>Sign</code> class is a utility for generating signatures. It can be used in one
of two ways:</p>
<ul>
<li>As a writable <a href="stream.html">stream</a>, where data to be signed is written and the
<a href="#crypto_sign_sign_privatekey_outputencoding"><code>sign.sign()</code></a> method is used to generate and return the signature, or</li>
<li>Using the <a href="#crypto_sign_update_data_inputencoding"><code>sign.update()</code></a> and <a href="#crypto_sign_sign_privatekey_outputencoding"><code>sign.sign()</code></a> methods to produce the
signature.</li>
</ul>
<p>The <a href="#crypto_crypto_createsign_algorithm_options"><code>crypto.createSign()</code></a> method is used to create <code>Sign</code> instances. The
argument is the string name of the hash function to use. <code>Sign</code> objects are not
to be created directly using the <code>new</code> keyword.</p>
<p>Example: Using <code>Sign</code> and <a href="#crypto_class_verify"><code>Verify</code></a> objects as streams:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> { privateKey, publicKey } = crypto.<span class="hljs-title function_">generateKeyPairSync</span>(<span class="hljs-string">'ec'</span>, {
  <span class="hljs-attr">namedCurve</span>: <span class="hljs-string">'sect239k1'</span>
});

<span class="hljs-keyword">const</span> sign = crypto.<span class="hljs-title function_">createSign</span>(<span class="hljs-string">'SHA256'</span>);
sign.<span class="hljs-title function_">write</span>(<span class="hljs-string">'some data to sign'</span>);
sign.<span class="hljs-title function_">end</span>();
<span class="hljs-keyword">const</span> signature = sign.<span class="hljs-title function_">sign</span>(privateKey, <span class="hljs-string">'hex'</span>);

<span class="hljs-keyword">const</span> verify = crypto.<span class="hljs-title function_">createVerify</span>(<span class="hljs-string">'SHA256'</span>);
verify.<span class="hljs-title function_">write</span>(<span class="hljs-string">'some data to sign'</span>);
verify.<span class="hljs-title function_">end</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(verify.<span class="hljs-title function_">verify</span>(publicKey, signature, <span class="hljs-string">'hex'</span>));
<span class="hljs-comment">// Prints: true</span></code></pre>
<p>Example: Using the <a href="#crypto_sign_update_data_inputencoding"><code>sign.update()</code></a> and <a href="#crypto_verify_update_data_inputencoding"><code>verify.update()</code></a> methods:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> { privateKey, publicKey } = crypto.<span class="hljs-title function_">generateKeyPairSync</span>(<span class="hljs-string">'rsa'</span>, {
  <span class="hljs-attr">modulusLength</span>: <span class="hljs-number">2048</span>,
});

<span class="hljs-keyword">const</span> sign = crypto.<span class="hljs-title function_">createSign</span>(<span class="hljs-string">'SHA256'</span>);
sign.<span class="hljs-title function_">update</span>(<span class="hljs-string">'some data to sign'</span>);
sign.<span class="hljs-title function_">end</span>();
<span class="hljs-keyword">const</span> signature = sign.<span class="hljs-title function_">sign</span>(privateKey);

<span class="hljs-keyword">const</span> verify = crypto.<span class="hljs-title function_">createVerify</span>(<span class="hljs-string">'SHA256'</span>);
verify.<span class="hljs-title function_">update</span>(<span class="hljs-string">'some data to sign'</span>);
verify.<span class="hljs-title function_">end</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(verify.<span class="hljs-title function_">verify</span>(publicKey, signature));
<span class="hljs-comment">// Prints: true</span></code></pre>
<h4><code>sign.sign(privateKey[, outputEncoding])</code><span><a class="mark" href="#crypto_sign_sign_privatekey_outputencoding" id="crypto_sign_sign_privatekey_outputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.2.0, v12.16.0</td>
<td><p>This function now supports IEEE-P1363 DSA and ECDSA signatures.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>This function now supports RSA-PSS keys.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p>This function now supports key objects.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>Support for RSASSA-PSS and additional options was added.</p></td></tr>
<tr><td>v0.1.92</td>
<td><p><span>Added in: v0.1.92</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>privateKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>dsaEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>padding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a></li>
<li><code>saltLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a></li>
</ul>
</li>
<li><code>outputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the return value.</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Calculates the signature on all the data passed through using either
<a href="#crypto_sign_update_data_inputencoding"><code>sign.update()</code></a> or <a href="stream.html#stream_writable_write_chunk_encoding_callback"><code>sign.write()</code></a>.</p>
<p>If <code>privateKey</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if
<code>privateKey</code> had been passed to <a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey()</code></a>. If it is an
object, the following additional properties can be passed:</p>
<ul>
<li>
<p><code>dsaEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> For DSA and ECDSA, this option specifies the
format of the generated signature. It can be one of the following:</p>
<ul>
<li><code>'der'</code> (default): DER-encoded ASN.1 signature structure encoding <code>(r, s)</code>.</li>
<li><code>'ieee-p1363'</code>: Signature format <code>r || s</code> as proposed in IEEE-P1363.</li>
</ul>
</li>
<li>
<p><code>padding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Optional padding value for RSA, one of the following:</p>
<ul>
<li><code>crypto.constants.RSA_PKCS1_PADDING</code> (default)</li>
<li><code>crypto.constants.RSA_PKCS1_PSS_PADDING</code></li>
</ul>
<p><code>RSA_PKCS1_PSS_PADDING</code> will use MGF1 with the same hash function
used to sign the message as specified in section 3.1 of <a href="https://www.rfc-editor.org/rfc/rfc4055.txt">RFC 4055</a>, unless
an MGF1 hash function has been specified as part of the key in compliance with
section 3.3 of <a href="https://www.rfc-editor.org/rfc/rfc4055.txt">RFC 4055</a>.</p>
</li>
<li>
<p><code>saltLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Salt length for when padding is
<code>RSA_PKCS1_PSS_PADDING</code>. The special value
<code>crypto.constants.RSA_PSS_SALTLEN_DIGEST</code> sets the salt length to the digest
size, <code>crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN</code> (default) sets it to the
maximum permissible value.</p>
</li>
</ul>
<p>If <code>outputEncoding</code> is provided a string is returned; otherwise a <a href="buffer.html"><code>Buffer</code></a>
is returned.</p>
<p>The <code>Sign</code> object can not be again used after <code>sign.sign()</code> method has been
called. Multiple calls to <code>sign.sign()</code> will result in an error being thrown.</p>
<h4><code>sign.update(data[, inputEncoding])</code><span><a class="mark" href="#crypto_sign_update_data_inputencoding" id="crypto_sign_update_data_inputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.1.92</td>
<td><p><span>Added in: v0.1.92</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>data</code> string.</li>
</ul>
<p>Updates the <code>Sign</code> content with the given <code>data</code>, the encoding of which
is given in <code>inputEncoding</code>.
If <code>encoding</code> is not provided, and the <code>data</code> is a string, an
encoding of <code>'utf8'</code> is enforced. If <code>data</code> is a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or
<code>DataView</code>, then <code>inputEncoding</code> is ignored.</p>
<p>This can be called many times with new data as it is streamed.</p>
</section><section><h3>Class: <code>Verify</code><span><a class="mark" href="#crypto_class_verify" id="crypto_class_verify">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.92</span>
</div>
<ul>
<li>Extends: <a href="stream.html#stream_class_stream_writable" class="type">&#x3C;stream.Writable></a></li>
</ul>
<p>The <code>Verify</code> class is a utility for verifying signatures. It can be used in one
of two ways:</p>
<ul>
<li>As a writable <a href="stream.html">stream</a> where written data is used to validate against the
supplied signature, or</li>
<li>Using the <a href="#crypto_verify_update_data_inputencoding"><code>verify.update()</code></a> and <a href="#crypto_verify_verify_object_signature_signatureencoding"><code>verify.verify()</code></a> methods to verify
the signature.</li>
</ul>
<p>The <a href="#crypto_crypto_createverify_algorithm_options"><code>crypto.createVerify()</code></a> method is used to create <code>Verify</code> instances.
<code>Verify</code> objects are not to be created directly using the <code>new</code> keyword.</p>
<p>See <a href="#crypto_class_sign"><code>Sign</code></a> for examples.</p>
<h4><code>verify.update(data[, inputEncoding])</code><span><a class="mark" href="#crypto_verify_update_data_inputencoding" id="crypto_verify_update_data_inputencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.0.0</td>
<td><p>The default <code>inputEncoding</code> changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.1.92</td>
<td><p><span>Added in: v0.1.92</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>inputEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>data</code> string.</li>
</ul>
<p>Updates the <code>Verify</code> content with the given <code>data</code>, the encoding of which
is given in <code>inputEncoding</code>.
If <code>inputEncoding</code> is not provided, and the <code>data</code> is a string, an
encoding of <code>'utf8'</code> is enforced. If <code>data</code> is a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or
<code>DataView</code>, then <code>inputEncoding</code> is ignored.</p>
<p>This can be called many times with new data as it is streamed.</p>
<h4><code>verify.verify(object, signature[, signatureEncoding])</code><span><a class="mark" href="#crypto_verify_verify_object_signature_signatureencoding" id="crypto_verify_verify_object_signature_signatureencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.2.0, v12.16.0</td>
<td><p>This function now supports IEEE-P1363 DSA and ECDSA signatures.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>This function now supports RSA-PSS keys.</p></td></tr>
<tr><td>v11.7.0</td>
<td><p>The key can now be a private key.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>Support for RSASSA-PSS and additional options was added.</p></td></tr>
<tr><td>v0.1.92</td>
<td><p><span>Added in: v0.1.92</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>object</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>dsaEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>padding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a></li>
<li><code>saltLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a></li>
</ul>
</li>
<li><code>signature</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>signatureEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>signature</code> string.</li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> <code>true</code> or <code>false</code> depending on the validity of the
signature for the data and public key.</li>
</ul>
<p>Verifies the provided data using the given <code>object</code> and <code>signature</code>.</p>
<p>If <code>object</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if
<code>object</code> had been passed to <a href="#crypto_crypto_createpublickey_key"><code>crypto.createPublicKey()</code></a>. If it is an
object, the following additional properties can be passed:</p>
<ul>
<li>
<p><code>dsaEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> For DSA and ECDSA, this option specifies the
format of the signature. It can be one of the following:</p>
<ul>
<li><code>'der'</code> (default): DER-encoded ASN.1 signature structure encoding <code>(r, s)</code>.</li>
<li><code>'ieee-p1363'</code>: Signature format <code>r || s</code> as proposed in IEEE-P1363.</li>
</ul>
</li>
<li>
<p><code>padding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Optional padding value for RSA, one of the following:</p>
<ul>
<li><code>crypto.constants.RSA_PKCS1_PADDING</code> (default)</li>
<li><code>crypto.constants.RSA_PKCS1_PSS_PADDING</code></li>
</ul>
<p><code>RSA_PKCS1_PSS_PADDING</code> will use MGF1 with the same hash function
used to verify the message as specified in section 3.1 of <a href="https://www.rfc-editor.org/rfc/rfc4055.txt">RFC 4055</a>, unless
an MGF1 hash function has been specified as part of the key in compliance with
section 3.3 of <a href="https://www.rfc-editor.org/rfc/rfc4055.txt">RFC 4055</a>.</p>
</li>
<li>
<p><code>saltLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Salt length for when padding is
<code>RSA_PKCS1_PSS_PADDING</code>. The special value
<code>crypto.constants.RSA_PSS_SALTLEN_DIGEST</code> sets the salt length to the digest
size, <code>crypto.constants.RSA_PSS_SALTLEN_AUTO</code> (default) causes it to be
determined automatically.</p>
</li>
</ul>
<p>The <code>signature</code> argument is the previously calculated signature for the data, in
the <code>signatureEncoding</code>.
If a <code>signatureEncoding</code> is specified, the <code>signature</code> is expected to be a
string; otherwise <code>signature</code> is expected to be a <a href="buffer.html"><code>Buffer</code></a>,
<code>TypedArray</code>, or <code>DataView</code>.</p>
<p>The <code>verify</code> object can not be used again after <code>verify.verify()</code> has been
called. Multiple calls to <code>verify.verify()</code> will result in an error being
thrown.</p>
<p>Because public keys can be derived from private keys, a private key may
be passed instead of a public key.</p>
</section><section><h3><code>crypto</code> module methods and properties<span><a class="mark" href="#crypto_crypto_module_methods_and_properties" id="crypto_crypto_module_methods_and_properties">#</a></span></h3>
<h4><code>crypto.constants</code><span><a class="mark" href="#crypto_crypto_constants" id="crypto_crypto_constants">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v6.3.0</span>
</div>
<ul>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> An object containing commonly used constants for crypto and
security related operations. The specific constants currently defined are
described in <a href="#crypto_crypto_constants_1">Crypto constants</a>.</li>
</ul>
<h4><code>crypto.DEFAULT_ENCODING</code><span><a class="mark" href="#crypto_crypto_default_encoding" id="crypto_crypto_default_encoding">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.9.3</span><span>Deprecated since: v10.0.0</span>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated</div><p></p>
<p>The default encoding to use for functions that can take either strings
or <a href="buffer.html">buffers</a>. The default value is <code>'buffer'</code>, which makes methods
default to <a href="buffer.html"><code>Buffer</code></a> objects.</p>
<p>The <code>crypto.DEFAULT_ENCODING</code> mechanism is provided for backward compatibility
with legacy programs that expect <code>'latin1'</code> to be the default encoding.</p>
<p>New applications should expect the default to be <code>'buffer'</code>.</p>
<p>This property is deprecated.</p>
<h4><code>crypto.fips</code><span><a class="mark" href="#crypto_crypto_fips" id="crypto_crypto_fips">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v6.0.0</span><span>Deprecated since: v10.0.0</span>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated</div><p></p>
<p>Property for checking and controlling whether a FIPS compliant crypto provider
is currently in use. Setting to true requires a FIPS build of Node.js.</p>
<p>This property is deprecated. Please use <code>crypto.setFips()</code> and
<code>crypto.getFips()</code> instead.</p>
<h4><code>crypto.createCipher(algorithm, password[, options])</code><span><a class="mark" href="#crypto_crypto_createcipher_algorithm_password_options" id="crypto_crypto_createcipher_algorithm_password_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.10.0</td>
<td><p>Ciphers in OCB mode are now supported.</p></td></tr>
<tr><td>v10.2.0</td>
<td><p>The <code>authTagLength</code> option can now be used to produce shorter authentication tags in GCM mode and defaults to 16 bytes.</p></td></tr>
<tr><td>v10.0.0</td>
<td><p><span>Deprecated since: v10.0.0</span></p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#crypto_crypto_createcipheriv_algorithm_key_iv_options"><code>crypto.createCipheriv()</code></a> instead.</div><p></p>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>password</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_cipher" class="type">&#x3C;Cipher></a></li>
</ul>
<p>Creates and returns a <code>Cipher</code> object that uses the given <code>algorithm</code> and
<code>password</code>.</p>
<p>The <code>options</code> argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode is used (e.g. <code>'aes-128-ccm'</code>). In that case, the
<code>authTagLength</code> option is required and specifies the length of the
authentication tag in bytes, see <a href="#crypto_ccm_mode">CCM mode</a>. In GCM mode, the <code>authTagLength</code>
option is not required but can be used to set the length of the authentication
tag that will be returned by <code>getAuthTag()</code> and defaults to 16 bytes.</p>
<p>The <code>algorithm</code> is dependent on OpenSSL, examples are <code>'aes192'</code>, etc. On
recent OpenSSL releases, <code>openssl list -cipher-algorithms</code>
(<code>openssl list-cipher-algorithms</code> for older versions of OpenSSL) will
display the available cipher algorithms.</p>
<p>The <code>password</code> is used to derive the cipher key and initialization vector (IV).
The value must be either a <code>'latin1'</code> encoded string, a <a href="buffer.html"><code>Buffer</code></a>, a
<code>TypedArray</code>, or a <code>DataView</code>.</p>
<p>The implementation of <code>crypto.createCipher()</code> derives keys using the OpenSSL
function <a href="https://www.openssl.org/docs/man1.1.0/crypto/EVP_BytesToKey.html"><code>EVP_BytesToKey</code></a> with the digest algorithm set to MD5, one
iteration, and no salt. The lack of salt allows dictionary attacks as the same
password always creates the same key. The low iteration count and
non-cryptographically secure hash algorithm allow passwords to be tested very
rapidly.</p>
<p>In line with OpenSSL's recommendation to use a more modern algorithm instead of
<a href="https://www.openssl.org/docs/man1.1.0/crypto/EVP_BytesToKey.html"><code>EVP_BytesToKey</code></a> it is recommended that developers derive a key and IV on
their own using <a href="#crypto_crypto_scrypt_password_salt_keylen_options_callback"><code>crypto.scrypt()</code></a> and to use <a href="#crypto_crypto_createcipheriv_algorithm_key_iv_options"><code>crypto.createCipheriv()</code></a>
to create the <code>Cipher</code> object. Users should not use ciphers with counter mode
(e.g. CTR, GCM, or CCM) in <code>crypto.createCipher()</code>. A warning is emitted when
they are used in order to avoid the risk of IV reuse that causes
vulnerabilities. For the case when IV is reused in GCM, see <a href="https://github.com/nonce-disrespect/nonce-disrespect">Nonce-Disrespecting
Adversaries</a> for details.</p>
<h4><code>crypto.createCipheriv(algorithm, key, iv[, options])</code><span><a class="mark" href="#crypto_crypto_createcipheriv_algorithm_key_iv_options" id="crypto_crypto_createcipheriv_algorithm_key_iv_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.6.0</td>
<td><p>The <code>key</code> argument can now be a <code>KeyObject</code>.</p></td></tr>
<tr><td>v11.2.0, v10.17.0</td>
<td><p>The cipher <code>chacha20-poly1305</code> is now supported.</p></td></tr>
<tr><td>v10.10.0</td>
<td><p>Ciphers in OCB mode are now supported.</p></td></tr>
<tr><td>v10.2.0</td>
<td><p>The <code>authTagLength</code> option can now be used to produce shorter authentication tags in GCM mode and defaults to 16 bytes.</p></td></tr>
<tr><td>v9.9.0</td>
<td><p>The <code>iv</code> parameter may now be <code>null</code> for ciphers which do not need an initialization vector.</p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>iv</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Null_type" class="type">&#x3C;null></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_cipher" class="type">&#x3C;Cipher></a></li>
</ul>
<p>Creates and returns a <code>Cipher</code> object, with the given <code>algorithm</code>, <code>key</code> and
initialization vector (<code>iv</code>).</p>
<p>The <code>options</code> argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode is used (e.g. <code>'aes-128-ccm'</code>). In that case, the
<code>authTagLength</code> option is required and specifies the length of the
authentication tag in bytes, see <a href="#crypto_ccm_mode">CCM mode</a>. In GCM mode, the <code>authTagLength</code>
option is not required but can be used to set the length of the authentication
tag that will be returned by <code>getAuthTag()</code> and defaults to 16 bytes.</p>
<p>The <code>algorithm</code> is dependent on OpenSSL, examples are <code>'aes192'</code>, etc. On
recent OpenSSL releases, <code>openssl list -cipher-algorithms</code>
(<code>openssl list-cipher-algorithms</code> for older versions of OpenSSL) will
display the available cipher algorithms.</p>
<p>The <code>key</code> is the raw key used by the <code>algorithm</code> and <code>iv</code> is an
<a href="https://en.wikipedia.org/wiki/Initialization_vector">initialization vector</a>. Both arguments must be <code>'utf8'</code> encoded strings,
<a href="buffer.html">Buffers</a>, <code>TypedArray</code>, or <code>DataView</code>s. The <code>key</code> may optionally be
a <a href="#crypto_class_keyobject"><code>KeyObject</code></a> of type <code>secret</code>. If the cipher does not need
an initialization vector, <code>iv</code> may be <code>null</code>.</p>
<p>Initialization vectors should be unpredictable and unique; ideally, they will be
cryptographically random. They do not have to be secret: IVs are typically just
added to ciphertext messages unencrypted. It may sound contradictory that
something has to be unpredictable and unique, but does not have to be secret;
remember that an attacker must not be able to predict ahead of time what a
given IV will be.</p>
<h4><code>crypto.createDecipher(algorithm, password[, options])</code><span><a class="mark" href="#crypto_crypto_createdecipher_algorithm_password_options" id="crypto_crypto_createdecipher_algorithm_password_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.10.0</td>
<td><p>Ciphers in OCB mode are now supported.</p></td></tr>
<tr><td>v10.0.0</td>
<td><p><span>Deprecated since: v10.0.0</span></p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#crypto_crypto_createdecipheriv_algorithm_key_iv_options"><code>crypto.createDecipheriv()</code></a> instead.</div><p></p>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>password</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_decipher" class="type">&#x3C;Decipher></a></li>
</ul>
<p>Creates and returns a <code>Decipher</code> object that uses the given <code>algorithm</code> and
<code>password</code> (key).</p>
<p>The <code>options</code> argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode is used (e.g. <code>'aes-128-ccm'</code>). In that case, the
<code>authTagLength</code> option is required and specifies the length of the
authentication tag in bytes, see <a href="#crypto_ccm_mode">CCM mode</a>.</p>
<p>The implementation of <code>crypto.createDecipher()</code> derives keys using the OpenSSL
function <a href="https://www.openssl.org/docs/man1.1.0/crypto/EVP_BytesToKey.html"><code>EVP_BytesToKey</code></a> with the digest algorithm set to MD5, one
iteration, and no salt. The lack of salt allows dictionary attacks as the same
password always creates the same key. The low iteration count and
non-cryptographically secure hash algorithm allow passwords to be tested very
rapidly.</p>
<p>In line with OpenSSL's recommendation to use a more modern algorithm instead of
<a href="https://www.openssl.org/docs/man1.1.0/crypto/EVP_BytesToKey.html"><code>EVP_BytesToKey</code></a> it is recommended that developers derive a key and IV on
their own using <a href="#crypto_crypto_scrypt_password_salt_keylen_options_callback"><code>crypto.scrypt()</code></a> and to use <a href="#crypto_crypto_createdecipheriv_algorithm_key_iv_options"><code>crypto.createDecipheriv()</code></a>
to create the <code>Decipher</code> object.</p>
<h4><code>crypto.createDecipheriv(algorithm, key, iv[, options])</code><span><a class="mark" href="#crypto_crypto_createdecipheriv_algorithm_key_iv_options" id="crypto_crypto_createdecipheriv_algorithm_key_iv_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.6.0</td>
<td><p>The <code>key</code> argument can now be a <code>KeyObject</code>.</p></td></tr>
<tr><td>v11.2.0, v10.17.0</td>
<td><p>The cipher <code>chacha20-poly1305</code> is now supported.</p></td></tr>
<tr><td>v10.10.0</td>
<td><p>Ciphers in OCB mode are now supported.</p></td></tr>
<tr><td>v10.2.0</td>
<td><p>The <code>authTagLength</code> option can now be used to restrict accepted GCM authentication tag lengths.</p></td></tr>
<tr><td>v9.9.0</td>
<td><p>The <code>iv</code> parameter may now be <code>null</code> for ciphers which do not need an initialization vector.</p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>iv</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Null_type" class="type">&#x3C;null></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_decipher" class="type">&#x3C;Decipher></a></li>
</ul>
<p>Creates and returns a <code>Decipher</code> object that uses the given <code>algorithm</code>, <code>key</code>
and initialization vector (<code>iv</code>).</p>
<p>The <code>options</code> argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode is used (e.g. <code>'aes-128-ccm'</code>). In that case, the
<code>authTagLength</code> option is required and specifies the length of the
authentication tag in bytes, see <a href="#crypto_ccm_mode">CCM mode</a>. In GCM mode, the <code>authTagLength</code>
option is not required but can be used to restrict accepted authentication tags
to those with the specified length.</p>
<p>The <code>algorithm</code> is dependent on OpenSSL, examples are <code>'aes192'</code>, etc. On
recent OpenSSL releases, <code>openssl list -cipher-algorithms</code>
(<code>openssl list-cipher-algorithms</code> for older versions of OpenSSL) will
display the available cipher algorithms.</p>
<p>The <code>key</code> is the raw key used by the <code>algorithm</code> and <code>iv</code> is an
<a href="https://en.wikipedia.org/wiki/Initialization_vector">initialization vector</a>. Both arguments must be <code>'utf8'</code> encoded strings,
<a href="buffer.html">Buffers</a>, <code>TypedArray</code>, or <code>DataView</code>s. The <code>key</code> may optionally be
a <a href="#crypto_class_keyobject"><code>KeyObject</code></a> of type <code>secret</code>. If the cipher does not need
an initialization vector, <code>iv</code> may be <code>null</code>.</p>
<p>Initialization vectors should be unpredictable and unique; ideally, they will be
cryptographically random. They do not have to be secret: IVs are typically just
added to ciphertext messages unencrypted. It may sound contradictory that
something has to be unpredictable and unique, but does not have to be secret;
remember that an attacker must not be able to predict ahead of time what a given
IV will be.</p>
<h4><code>crypto.createDiffieHellman(prime[, primeEncoding][, generator][, generatorEncoding])</code><span><a class="mark" href="#crypto_crypto_creatediffiehellman_prime_primeencoding_generator_generatorencoding" id="crypto_crypto_creatediffiehellman_prime_primeencoding_generator_generatorencoding">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>prime</code> argument can be any <code>TypedArray</code> or <code>DataView</code> now.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>prime</code> argument can be a <code>Uint8Array</code> now.</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>The default for the encoding parameters changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.11.12</td>
<td><p><span>Added in: v0.11.12</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>prime</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>primeEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>prime</code> string.</li>
<li><code>generator</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> <strong>Default:</strong>
<code>2</code></li>
<li><code>generatorEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <a href="buffer.html#buffer_buffers_and_character_encodings">encoding</a> of the <code>generator</code> string.</li>
<li>Returns: <a href="crypto.html#crypto_class_diffiehellman" class="type">&#x3C;DiffieHellman></a></li>
</ul>
<p>Creates a <code>DiffieHellman</code> key exchange object using the supplied <code>prime</code> and an
optional specific <code>generator</code>.</p>
<p>The <code>generator</code> argument can be a number, string, or <a href="buffer.html"><code>Buffer</code></a>. If
<code>generator</code> is not specified, the value <code>2</code> is used.</p>
<p>If <code>primeEncoding</code> is specified, <code>prime</code> is expected to be a string; otherwise
a <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or <code>DataView</code> is expected.</p>
<p>If <code>generatorEncoding</code> is specified, <code>generator</code> is expected to be a string;
otherwise a number, <a href="buffer.html"><code>Buffer</code></a>, <code>TypedArray</code>, or <code>DataView</code> is expected.</p>
<h4><code>crypto.createDiffieHellman(primeLength[, generator])</code><span><a class="mark" href="#crypto_crypto_creatediffiehellman_primelength_generator" id="crypto_crypto_creatediffiehellman_primelength_generator">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.5.0</span>
</div>
<ul>
<li><code>primeLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>generator</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <strong>Default:</strong> <code>2</code></li>
<li>Returns: <a href="crypto.html#crypto_class_diffiehellman" class="type">&#x3C;DiffieHellman></a></li>
</ul>
<p>Creates a <code>DiffieHellman</code> key exchange object and generates a prime of
<code>primeLength</code> bits using an optional specific numeric <code>generator</code>.
If <code>generator</code> is not specified, the value <code>2</code> is used.</p>
<h4><code>crypto.createDiffieHellmanGroup(name)</code><span><a class="mark" href="#crypto_crypto_creatediffiehellmangroup_name" id="crypto_crypto_creatediffiehellmangroup_name">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.9.3</span>
</div>
<ul>
<li><code>name</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li>Returns: <a href="crypto.html#crypto_class_diffiehellmangroup" class="type">&#x3C;DiffieHellmanGroup></a></li>
</ul>
<p>An alias for <a href="#crypto_crypto_getdiffiehellman_groupname"><code>crypto.getDiffieHellman()</code></a></p>
<h4><code>crypto.createECDH(curveName)</code><span><a class="mark" href="#crypto_crypto_createecdh_curvename" id="crypto_crypto_createecdh_curvename">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.14</span>
</div>
<ul>
<li><code>curveName</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li>Returns: <a href="crypto.html#crypto_class_ecdh" class="type">&#x3C;ECDH></a></li>
</ul>
<p>Creates an Elliptic Curve Diffie-Hellman (<code>ECDH</code>) key exchange object using a
predefined curve specified by the <code>curveName</code> string. Use
<a href="#crypto_crypto_getcurves"><code>crypto.getCurves()</code></a> to obtain a list of available curve names. On recent
OpenSSL releases, <code>openssl ecparam -list_curves</code> will also display the name
and description of each available elliptic curve.</p>
<h4><code>crypto.createHash(algorithm[, options])</code><span><a class="mark" href="#crypto_crypto_createhash_algorithm_options" id="crypto_crypto_createhash_algorithm_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v12.8.0</td>
<td><p>The <code>outputLength</code> option was added for XOF hash functions.</p></td></tr>
<tr><td>v0.1.92</td>
<td><p><span>Added in: v0.1.92</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_hash" class="type">&#x3C;Hash></a></li>
</ul>
<p>Creates and returns a <code>Hash</code> object that can be used to generate hash digests
using the given <code>algorithm</code>. Optional <code>options</code> argument controls stream
behavior. For XOF hash functions such as <code>'shake256'</code>, the <code>outputLength</code> option
can be used to specify the desired output length in bytes.</p>
<p>The <code>algorithm</code> is dependent on the available algorithms supported by the
version of OpenSSL on the platform. Examples are <code>'sha256'</code>, <code>'sha512'</code>, etc.
On recent releases of OpenSSL, <code>openssl list -digest-algorithms</code>
(<code>openssl list-message-digest-algorithms</code> for older versions of OpenSSL) will
display the available digest algorithms.</p>
<p>Example: generating the sha256 sum of a file</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> filename = process.<span class="hljs-property">argv</span>[<span class="hljs-number">2</span>];
<span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>);

<span class="hljs-keyword">const</span> hash = crypto.<span class="hljs-title function_">createHash</span>(<span class="hljs-string">'sha256'</span>);

<span class="hljs-keyword">const</span> input = fs.<span class="hljs-title function_">createReadStream</span>(filename);
input.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-comment">// Only one element is going to be produced by the</span>
  <span class="hljs-comment">// hash stream.</span>
  <span class="hljs-keyword">const</span> data = input.<span class="hljs-title function_">read</span>();
  <span class="hljs-keyword">if</span> (data)
    hash.<span class="hljs-title function_">update</span>(data);
  <span class="hljs-keyword">else</span> {
    <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`<span class="hljs-subst">${hash.digest(<span class="hljs-string">'hex'</span>)}</span> <span class="hljs-subst">${filename}</span>`</span>);
  }
});</code></pre>
<h4><code>crypto.createHmac(algorithm, key[, options])</code><span><a class="mark" href="#crypto_crypto_createhmac_algorithm_key_options" id="crypto_crypto_createhmac_algorithm_key_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.6.0</td>
<td><p>The <code>key</code> argument can now be a <code>KeyObject</code>.</p></td></tr>
<tr><td>v0.1.94</td>
<td><p><span>Added in: v0.1.94</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_transform_options"><code>stream.transform</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_hmac" class="type">&#x3C;Hmac></a></li>
</ul>
<p>Creates and returns an <code>Hmac</code> object that uses the given <code>algorithm</code> and <code>key</code>.
Optional <code>options</code> argument controls stream behavior.</p>
<p>The <code>algorithm</code> is dependent on the available algorithms supported by the
version of OpenSSL on the platform. Examples are <code>'sha256'</code>, <code>'sha512'</code>, etc.
On recent releases of OpenSSL, <code>openssl list -digest-algorithms</code>
(<code>openssl list-message-digest-algorithms</code> for older versions of OpenSSL) will
display the available digest algorithms.</p>
<p>The <code>key</code> is the HMAC key used to generate the cryptographic HMAC hash. If it is
a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, its type must be <code>secret</code>.</p>
<p>Example: generating the sha256 HMAC of a file</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> filename = process.<span class="hljs-property">argv</span>[<span class="hljs-number">2</span>];
<span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>);

<span class="hljs-keyword">const</span> hmac = crypto.<span class="hljs-title function_">createHmac</span>(<span class="hljs-string">'sha256'</span>, <span class="hljs-string">'a secret'</span>);

<span class="hljs-keyword">const</span> input = fs.<span class="hljs-title function_">createReadStream</span>(filename);
input.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> {
  <span class="hljs-comment">// Only one element is going to be produced by the</span>
  <span class="hljs-comment">// hash stream.</span>
  <span class="hljs-keyword">const</span> data = input.<span class="hljs-title function_">read</span>();
  <span class="hljs-keyword">if</span> (data)
    hmac.<span class="hljs-title function_">update</span>(data);
  <span class="hljs-keyword">else</span> {
    <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`<span class="hljs-subst">${hmac.digest(<span class="hljs-string">'hex'</span>)}</span> <span class="hljs-subst">${filename}</span>`</span>);
  }
});</code></pre>
<h4><code>crypto.createPrivateKey(key)</code><span><a class="mark" href="#crypto_crypto_createprivatekey_key" id="crypto_crypto_createprivatekey_key">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v11.6.0</span>
</div>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a>
<ul>
<li><code>key</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The key material, either in PEM or DER format.</li>
<li><code>format</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'pem'</code> or <code>'der'</code>. <strong>Default:</strong> <code>'pem'</code>.</li>
<li><code>type</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'pkcs1'</code>, <code>'pkcs8'</code> or <code>'sec1'</code>. This option is
required only if the <code>format</code> is <code>'der'</code> and ignored if it is <code>'pem'</code>.</li>
<li><code>passphrase</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The passphrase to use for decryption.</li>
</ul>
</li>
<li>Returns: <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
</ul>
<p>Creates and returns a new key object containing a private key. If <code>key</code> is a
string or <code>Buffer</code>, <code>format</code> is assumed to be <code>'pem'</code>; otherwise, <code>key</code>
must be an object with the properties described above.</p>
<p>If the private key is encrypted, a <code>passphrase</code> must be specified. The length
of the passphrase is limited to 1024 bytes.</p>
<h4><code>crypto.createPublicKey(key)</code><span><a class="mark" href="#crypto_crypto_createpublickey_key" id="crypto_crypto_createpublickey_key">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.13.0</td>
<td><p>The <code>key</code> argument can now be a <code>KeyObject</code> with type <code>private</code>.</p></td></tr>
<tr><td>v11.7.0</td>
<td><p>The <code>key</code> argument can now be a private key.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p><span>Added in: v11.6.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>key</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
<li><code>format</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'pem'</code> or <code>'der'</code>. <strong>Default:</strong> <code>'pem'</code>.</li>
<li><code>type</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'pkcs1'</code> or <code>'spki'</code>. This option is required
only if the <code>format</code> is <code>'der'</code>.</li>
</ul>
</li>
<li>Returns: <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
</ul>
<p>Creates and returns a new key object containing a public key. If <code>key</code> is a
string or <code>Buffer</code>, <code>format</code> is assumed to be <code>'pem'</code>; if <code>key</code> is a <code>KeyObject</code>
with type <code>'private'</code>, the public key is derived from the given private key;
otherwise, <code>key</code> must be an object with the properties described above.</p>
<p>If the format is <code>'pem'</code>, the <code>'key'</code> may also be an X.509 certificate.</p>
<p>Because public keys can be derived from private keys, a private key may be
passed instead of a public key. In that case, this function behaves as if
<a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey()</code></a> had been called, except that the type of the
returned <code>KeyObject</code> will be <code>'public'</code> and that the private key cannot be
extracted from the returned <code>KeyObject</code>. Similarly, if a <code>KeyObject</code> with type
<code>'private'</code> is given, a new <code>KeyObject</code> with type <code>'public'</code> will be returned
and it will be impossible to extract the private key from the returned object.</p>
<h4><code>crypto.createSecretKey(key)</code><span><a class="mark" href="#crypto_crypto_createsecretkey_key" id="crypto_crypto_createsecretkey_key">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v11.6.0</span>
</div>
<ul>
<li><code>key</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
</ul>
<p>Creates and returns a new key object containing a secret key for symmetric
encryption or <code>Hmac</code>.</p>
<h4><code>crypto.createSign(algorithm[, options])</code><span><a class="mark" href="#crypto_crypto_createsign_algorithm_options" id="crypto_crypto_createsign_algorithm_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.1.92</span>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_writable_options"><code>stream.Writable</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_sign" class="type">&#x3C;Sign></a></li>
</ul>
<p>Creates and returns a <code>Sign</code> object that uses the given <code>algorithm</code>. Use
<a href="#crypto_crypto_gethashes"><code>crypto.getHashes()</code></a> to obtain the names of the available digest algorithms.
Optional <code>options</code> argument controls the <code>stream.Writable</code> behavior.</p>
<p>In some cases, a <code>Sign</code> instance can be created using the name of a signature
algorithm, such as <code>'RSA-SHA256'</code>, instead of a digest algorithm. This will use
the corresponding digest algorithm. This does not work for all signature
algorithms, such as <code>'ecdsa-with-SHA256'</code>, so it is best to always use digest
algorithm names.</p>
<h4><code>crypto.createVerify(algorithm[, options])</code><span><a class="mark" href="#crypto_crypto_createverify_algorithm_options" id="crypto_crypto_createverify_algorithm_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.1.92</span>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> <a href="stream.html#stream_new_stream_writable_options"><code>stream.Writable</code> options</a></li>
<li>Returns: <a href="crypto.html#crypto_class_verify" class="type">&#x3C;Verify></a></li>
</ul>
<p>Creates and returns a <code>Verify</code> object that uses the given algorithm.
Use <a href="#crypto_crypto_gethashes"><code>crypto.getHashes()</code></a> to obtain an array of names of the available
signing algorithms. Optional <code>options</code> argument controls the
<code>stream.Writable</code> behavior.</p>
<p>In some cases, a <code>Verify</code> instance can be created using the name of a signature
algorithm, such as <code>'RSA-SHA256'</code>, instead of a digest algorithm. This will use
the corresponding digest algorithm. This does not work for all signature
algorithms, such as <code>'ecdsa-with-SHA256'</code>, so it is best to always use digest
algorithm names.</p>
<h4><code>crypto.diffieHellman(options)</code><span><a class="mark" href="#crypto_crypto_diffiehellman_options" id="crypto_crypto_diffiehellman_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v13.9.0</span>
</div>
<ul>
<li><code>options</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>privateKey</code>: <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>publicKey</code>: <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
</ul>
</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
<p>Computes the Diffie-Hellman secret based on a <code>privateKey</code> and a <code>publicKey</code>.
Both keys must have the same <code>asymmetricKeyType</code>, which must be one of <code>'dh'</code>
(for Diffie-Hellman), <code>'ec'</code> (for ECDH), <code>'x448'</code>, or <code>'x25519'</code> (for ECDH-ES).</p>
<h4><code>crypto.generateKeyPair(type, options, callback)</code><span><a class="mark" href="#crypto_crypto_generatekeypair_type_options_callback" id="crypto_crypto_generatekeypair_type_options_callback">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.9.0</td>
<td><p>Add support for Diffie-Hellman.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>Add ability to generate X25519 and X448 key pairs.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>Add ability to generate Ed25519 and Ed448 key pairs.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p>The <code>generateKeyPair</code> and <code>generateKeyPairSync</code> functions now produce key objects if no encoding was specified.</p></td></tr>
<tr><td>v10.12.0</td>
<td><p><span>Added in: v10.12.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>type</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'rsa'</code>, <code>'dsa'</code>, <code>'ec'</code>, <code>'ed25519'</code>, <code>'ed448'</code>,
<code>'x25519'</code>, <code>'x448'</code>, or <code>'dh'</code>.</li>
<li><code>options</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>modulusLength</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Key size in bits (RSA, DSA).</li>
<li><code>publicExponent</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Public exponent (RSA). <strong>Default:</strong> <code>0x10001</code>.</li>
<li><code>divisorLength</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Size of <code>q</code> in bits (DSA).</li>
<li><code>namedCurve</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Name of the curve to use (EC).</li>
<li><code>prime</code>: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The prime parameter (DH).</li>
<li><code>primeLength</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Prime length in bits (DH).</li>
<li><code>generator</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Custom generator (DH). <strong>Default:</strong> <code>2</code>.</li>
<li><code>groupName</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Diffie-Hellman group name (DH). See
<a href="#crypto_crypto_getdiffiehellman_groupname"><code>crypto.getDiffieHellman()</code></a>.</li>
<li><code>publicKeyEncoding</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> See <a href="#crypto_keyobject_export_options"><code>keyObject.export()</code></a>.</li>
<li><code>privateKeyEncoding</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> See <a href="#crypto_keyobject_export_options"><code>keyObject.export()</code></a>.</li>
</ul>
</li>
<li><code>callback</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a>
<ul>
<li><code>err</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>publicKey</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>privateKey</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
</ul>
</li>
</ul>
<p>Generates a new asymmetric key pair of the given <code>type</code>. RSA, DSA, EC, Ed25519,
Ed448, X25519, X448, and DH are currently supported.</p>
<p>If a <code>publicKeyEncoding</code> or <code>privateKeyEncoding</code> was specified, this function
behaves as if <a href="#crypto_keyobject_export_options"><code>keyObject.export()</code></a> had been called on its result. Otherwise,
the respective part of the key is returned as a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>.</p>
<p>It is recommended to encode public keys as <code>'spki'</code> and private keys as
<code>'pkcs8'</code> with encryption for long-term storage:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { generateKeyPair } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-title function_">generateKeyPair</span>(<span class="hljs-string">'rsa'</span>, {
  <span class="hljs-attr">modulusLength</span>: <span class="hljs-number">4096</span>,
  <span class="hljs-attr">publicKeyEncoding</span>: {
    <span class="hljs-attr">type</span>: <span class="hljs-string">'spki'</span>,
    <span class="hljs-attr">format</span>: <span class="hljs-string">'pem'</span>
  },
  <span class="hljs-attr">privateKeyEncoding</span>: {
    <span class="hljs-attr">type</span>: <span class="hljs-string">'pkcs8'</span>,
    <span class="hljs-attr">format</span>: <span class="hljs-string">'pem'</span>,
    <span class="hljs-attr">cipher</span>: <span class="hljs-string">'aes-256-cbc'</span>,
    <span class="hljs-attr">passphrase</span>: <span class="hljs-string">'top secret'</span>
  }
}, <span class="hljs-function">(<span class="hljs-params">err, publicKey, privateKey</span>) =></span> {
  <span class="hljs-comment">// Handle errors and use the generated key pair.</span>
});</code></pre>
<p>On completion, <code>callback</code> will be called with <code>err</code> set to <code>undefined</code> and
<code>publicKey</code> / <code>privateKey</code> representing the generated key pair.</p>
<p>If this method is invoked as its <a href="util.html#util_util_promisify_original"><code>util.promisify()</code></a>ed version, it returns
a <code>Promise</code> for an <code>Object</code> with <code>publicKey</code> and <code>privateKey</code> properties.</p>
<h4><code>crypto.generateKeyPairSync(type, options)</code><span><a class="mark" href="#crypto_crypto_generatekeypairsync_type_options" id="crypto_crypto_generatekeypairsync_type_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.9.0</td>
<td><p>Add support for Diffie-Hellman.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>Add ability to generate Ed25519 and Ed448 key pairs.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p>The <code>generateKeyPair</code> and <code>generateKeyPairSync</code> functions now produce key objects if no encoding was specified.</p></td></tr>
<tr><td>v10.12.0</td>
<td><p><span>Added in: v10.12.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>type</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Must be <code>'rsa'</code>, <code>'dsa'</code>, <code>'ec'</code>, <code>'ed25519'</code>, <code>'ed448'</code>,
<code>'x25519'</code>, <code>'x448'</code>, or <code>'dh'</code>.</li>
<li><code>options</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>modulusLength</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Key size in bits (RSA, DSA).</li>
<li><code>publicExponent</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Public exponent (RSA). <strong>Default:</strong> <code>0x10001</code>.</li>
<li><code>divisorLength</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Size of <code>q</code> in bits (DSA).</li>
<li><code>namedCurve</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Name of the curve to use (EC).</li>
<li><code>prime</code>: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> The prime parameter (DH).</li>
<li><code>primeLength</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Prime length in bits (DH).</li>
<li><code>generator</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Custom generator (DH). <strong>Default:</strong> <code>2</code>.</li>
<li><code>groupName</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Diffie-Hellman group name (DH). See
<a href="#crypto_crypto_getdiffiehellman_groupname"><code>crypto.getDiffieHellman()</code></a>.</li>
<li><code>publicKeyEncoding</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> See <a href="#crypto_keyobject_export_options"><code>keyObject.export()</code></a>.</li>
<li><code>privateKeyEncoding</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> See <a href="#crypto_keyobject_export_options"><code>keyObject.export()</code></a>.</li>
</ul>
</li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>publicKey</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>privateKey</code>: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
</ul>
</li>
</ul>
<p>Generates a new asymmetric key pair of the given <code>type</code>. RSA, DSA, EC, Ed25519,
Ed448, X25519, X448, and DH are currently supported.</p>
<p>If a <code>publicKeyEncoding</code> or <code>privateKeyEncoding</code> was specified, this function
behaves as if <a href="#crypto_keyobject_export_options"><code>keyObject.export()</code></a> had been called on its result. Otherwise,
the respective part of the key is returned as a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>.</p>
<p>When encoding public keys, it is recommended to use <code>'spki'</code>. When encoding
private keys, it is recommended to use <code>'pkcs8'</code> with a strong passphrase,
and to keep the passphrase confidential.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { generateKeyPairSync } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> { publicKey, privateKey } = <span class="hljs-title function_">generateKeyPairSync</span>(<span class="hljs-string">'rsa'</span>, {
  <span class="hljs-attr">modulusLength</span>: <span class="hljs-number">4096</span>,
  <span class="hljs-attr">publicKeyEncoding</span>: {
    <span class="hljs-attr">type</span>: <span class="hljs-string">'spki'</span>,
    <span class="hljs-attr">format</span>: <span class="hljs-string">'pem'</span>
  },
  <span class="hljs-attr">privateKeyEncoding</span>: {
    <span class="hljs-attr">type</span>: <span class="hljs-string">'pkcs8'</span>,
    <span class="hljs-attr">format</span>: <span class="hljs-string">'pem'</span>,
    <span class="hljs-attr">cipher</span>: <span class="hljs-string">'aes-256-cbc'</span>,
    <span class="hljs-attr">passphrase</span>: <span class="hljs-string">'top secret'</span>
  }
});</code></pre>
<p>The return value <code>{ publicKey, privateKey }</code> represents the generated key pair.
When PEM encoding was selected, the respective key will be a string, otherwise
it will be a buffer containing the data encoded as DER.</p>
<h4><code>crypto.getCiphers()</code><span><a class="mark" href="#crypto_crypto_getciphers" id="crypto_crypto_getciphers">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.9.3</span>
</div>
<ul>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string[]></a> An array with the names of the supported cipher
algorithms.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> ciphers = crypto.<span class="hljs-title function_">getCiphers</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(ciphers); <span class="hljs-comment">// ['aes-128-cbc', 'aes-128-ccm', ...]</span></code></pre>
<h4><code>crypto.getCurves()</code><span><a class="mark" href="#crypto_crypto_getcurves" id="crypto_crypto_getcurves">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v2.3.0</span>
</div>
<ul>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string[]></a> An array with the names of the supported elliptic curves.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> curves = crypto.<span class="hljs-title function_">getCurves</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(curves); <span class="hljs-comment">// ['Oakley-EC2N-3', 'Oakley-EC2N-4', ...]</span></code></pre>
<h4><code>crypto.getDiffieHellman(groupName)</code><span><a class="mark" href="#crypto_crypto_getdiffiehellman_groupname" id="crypto_crypto_getdiffiehellman_groupname">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.7.5</span>
</div>
<ul>
<li><code>groupName</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li>Returns: <a href="crypto.html#crypto_class_diffiehellmangroup" class="type">&#x3C;DiffieHellmanGroup></a></li>
</ul>
<p>Creates a predefined <code>DiffieHellmanGroup</code> key exchange object. The
supported groups are: <code>'modp1'</code>, <code>'modp2'</code>, <code>'modp5'</code> (defined in
<a href="https://www.rfc-editor.org/rfc/rfc2412.txt">RFC 2412</a>, but see <a href="#crypto_support_for_weak_or_compromised_algorithms">Caveats</a>) and <code>'modp14'</code>, <code>'modp15'</code>,
<code>'modp16'</code>, <code>'modp17'</code>, <code>'modp18'</code> (defined in <a href="https://www.rfc-editor.org/rfc/rfc3526.txt">RFC 3526</a>). The
returned object mimics the interface of objects created by
<a href="#crypto_crypto_creatediffiehellman_prime_primeencoding_generator_generatorencoding"><code>crypto.createDiffieHellman()</code></a>, but will not allow changing
the keys (with <a href="#crypto_diffiehellman_setpublickey_publickey_encoding"><code>diffieHellman.setPublicKey()</code></a>, for example). The
advantage of using this method is that the parties do not have to
generate nor exchange a group modulus beforehand, saving both processor
and communication time.</p>
<p>Example (obtaining a shared secret):</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> alice = crypto.<span class="hljs-title function_">getDiffieHellman</span>(<span class="hljs-string">'modp14'</span>);
<span class="hljs-keyword">const</span> bob = crypto.<span class="hljs-title function_">getDiffieHellman</span>(<span class="hljs-string">'modp14'</span>);

alice.<span class="hljs-title function_">generateKeys</span>();
bob.<span class="hljs-title function_">generateKeys</span>();

<span class="hljs-keyword">const</span> aliceSecret = alice.<span class="hljs-title function_">computeSecret</span>(bob.<span class="hljs-title function_">getPublicKey</span>(), <span class="hljs-literal">null</span>, <span class="hljs-string">'hex'</span>);
<span class="hljs-keyword">const</span> bobSecret = bob.<span class="hljs-title function_">computeSecret</span>(alice.<span class="hljs-title function_">getPublicKey</span>(), <span class="hljs-literal">null</span>, <span class="hljs-string">'hex'</span>);

<span class="hljs-comment">/* aliceSecret and bobSecret should be the same */</span>
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(aliceSecret === bobSecret);</code></pre>
<h4><code>crypto.getFips()</code><span><a class="mark" href="#crypto_crypto_getfips" id="crypto_crypto_getfips">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v10.0.0</span>
</div>
<ul>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <code>1</code> if and only if a FIPS compliant crypto provider is
currently in use, <code>0</code> otherwise. A future semver-major release may change
the return type of this API to a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a>.</li>
</ul>
<h4><code>crypto.getHashes()</code><span><a class="mark" href="#crypto_crypto_gethashes" id="crypto_crypto_gethashes">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.9.3</span>
</div>
<ul>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string[]></a> An array of the names of the supported hash algorithms,
such as <code>'RSA-SHA256'</code>. Hash algorithms are also called "digest" algorithms.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> hashes = crypto.<span class="hljs-title function_">getHashes</span>();
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(hashes); <span class="hljs-comment">// ['DSA', 'DSA-SHA', 'DSA-SHA1', ...]</span></code></pre>
<h4><code>crypto.pbkdf2(password, salt, iterations, keylen, digest, callback)</code><span><a class="mark" href="#crypto_crypto_pbkdf2_password_salt_iterations_keylen_digest_callback" id="crypto_crypto_pbkdf2_password_salt_iterations_keylen_digest_callback">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v14.0.0</td>
<td><p>The <code>iterations</code> parameter is now restricted to positive values. Earlier releases treated other values as one.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>digest</code> parameter is always required now.</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>Calling this function without passing the <code>digest</code> parameter is deprecated now and will emit a warning.</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>The default encoding for <code>password</code> if it is a string changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.5.5</td>
<td><p><span>Added in: v0.5.5</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>password</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>salt</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>iterations</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>keylen</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>digest</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a>
<ul>
<li><code>err</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>derivedKey</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
</li>
</ul>
<p>Provides an asynchronous Password-Based Key Derivation Function 2 (PBKDF2)
implementation. A selected HMAC digest algorithm specified by <code>digest</code> is
applied to derive a key of the requested byte length (<code>keylen</code>) from the
<code>password</code>, <code>salt</code> and <code>iterations</code>.</p>
<p>The supplied <code>callback</code> function is called with two arguments: <code>err</code> and
<code>derivedKey</code>. If an error occurs while deriving the key, <code>err</code> will be set;
otherwise <code>err</code> will be <code>null</code>. By default, the successfully generated
<code>derivedKey</code> will be passed to the callback as a <a href="buffer.html"><code>Buffer</code></a>. An error will be
thrown if any of the input arguments specify invalid values or types.</p>
<p>If <code>digest</code> is <code>null</code>, <code>'sha1'</code> will be used. This behavior is deprecated,
please specify a <code>digest</code> explicitly.</p>
<p>The <code>iterations</code> argument must be a number set as high as possible. The
higher the number of iterations, the more secure the derived key will be,
but will take a longer amount of time to complete.</p>
<p>The <code>salt</code> should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See <a href="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf">NIST SP 800-132</a> for details.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
crypto.<span class="hljs-title function_">pbkdf2</span>(<span class="hljs-string">'secret'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">100000</span>, <span class="hljs-number">64</span>, <span class="hljs-string">'sha512'</span>, <span class="hljs-function">(<span class="hljs-params">err, derivedKey</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(derivedKey.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));  <span class="hljs-comment">// '3745e48...08d59ae'</span>
});</code></pre>
<p>The <code>crypto.DEFAULT_ENCODING</code> property can be used to change the way the
<code>derivedKey</code> is passed to the callback. This property, however, has been
deprecated and use should be avoided.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
crypto.<span class="hljs-property">DEFAULT_ENCODING</span> = <span class="hljs-string">'hex'</span>;
crypto.<span class="hljs-title function_">pbkdf2</span>(<span class="hljs-string">'secret'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">100000</span>, <span class="hljs-number">512</span>, <span class="hljs-string">'sha512'</span>, <span class="hljs-function">(<span class="hljs-params">err, derivedKey</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(derivedKey);  <span class="hljs-comment">// '3745e48...aa39b34'</span>
});</code></pre>
<p>An array of supported digest functions can be retrieved using
<a href="#crypto_crypto_gethashes"><code>crypto.getHashes()</code></a>.</p>
<p>This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the
<a href="cli.html#cli_uv_threadpool_size_size"><code>UV_THREADPOOL_SIZE</code></a> documentation for more information.</p>
<h4><code>crypto.pbkdf2Sync(password, salt, iterations, keylen, digest)</code><span><a class="mark" href="#crypto_crypto_pbkdf2sync_password_salt_iterations_keylen_digest" id="crypto_crypto_pbkdf2sync_password_salt_iterations_keylen_digest">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v14.0.0</td>
<td><p>The <code>iterations</code> parameter is now restricted to positive values. Earlier releases treated other values as one.</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>Calling this function without passing the <code>digest</code> parameter is deprecated now and will emit a warning.</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>The default encoding for <code>password</code> if it is a string changed from <code>binary</code> to <code>utf8</code>.</p></td></tr>
<tr><td>v0.9.3</td>
<td><p><span>Added in: v0.9.3</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>password</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>salt</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>iterations</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>keylen</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>digest</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
<p>Provides a synchronous Password-Based Key Derivation Function 2 (PBKDF2)
implementation. A selected HMAC digest algorithm specified by <code>digest</code> is
applied to derive a key of the requested byte length (<code>keylen</code>) from the
<code>password</code>, <code>salt</code> and <code>iterations</code>.</p>
<p>If an error occurs an <code>Error</code> will be thrown, otherwise the derived key will be
returned as a <a href="buffer.html"><code>Buffer</code></a>.</p>
<p>If <code>digest</code> is <code>null</code>, <code>'sha1'</code> will be used. This behavior is deprecated,
please specify a <code>digest</code> explicitly.</p>
<p>The <code>iterations</code> argument must be a number set as high as possible. The
higher the number of iterations, the more secure the derived key will be,
but will take a longer amount of time to complete.</p>
<p>The <code>salt</code> should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See <a href="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf">NIST SP 800-132</a> for details.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">pbkdf2Sync</span>(<span class="hljs-string">'secret'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">100000</span>, <span class="hljs-number">64</span>, <span class="hljs-string">'sha512'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(key.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));  <span class="hljs-comment">// '3745e48...08d59ae'</span></code></pre>
<p>The <code>crypto.DEFAULT_ENCODING</code> property may be used to change the way the
<code>derivedKey</code> is returned. This property, however, is deprecated and use
should be avoided.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
crypto.<span class="hljs-property">DEFAULT_ENCODING</span> = <span class="hljs-string">'hex'</span>;
<span class="hljs-keyword">const</span> key = crypto.<span class="hljs-title function_">pbkdf2Sync</span>(<span class="hljs-string">'secret'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">100000</span>, <span class="hljs-number">512</span>, <span class="hljs-string">'sha512'</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(key);  <span class="hljs-comment">// '3745e48...aa39b34'</span></code></pre>
<p>An array of supported digest functions can be retrieved using
<a href="#crypto_crypto_gethashes"><code>crypto.getHashes()</code></a>.</p>
<h4><code>crypto.privateDecrypt(privateKey, buffer)</code><span><a class="mark" href="#crypto_crypto_privatedecrypt_privatekey_buffer" id="crypto_crypto_privatedecrypt_privatekey_buffer">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v12.11.0</td>
<td><p>The <code>oaepLabel</code> option was added.</p></td></tr>
<tr><td>v12.9.0</td>
<td><p>The <code>oaepHash</code> option was added.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p>This function now supports key objects.</p></td></tr>
<tr><td>v0.11.14</td>
<td><p><span>Added in: v0.11.14</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>privateKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>oaepHash</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The hash function to use for OAEP padding and MGF1.
<strong>Default:</strong> <code>'sha1'</code></li>
<li><code>oaepLabel</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> The label to use for OAEP
padding. If not specified, no label is used.</li>
<li><code>padding</code> <a href="crypto.html#crypto_crypto_constants_1" class="type">&#x3C;crypto.constants></a> An optional padding value defined in
<code>crypto.constants</code>, which may be: <code>crypto.constants.RSA_NO_PADDING</code>,
<code>crypto.constants.RSA_PKCS1_PADDING</code>, or
<code>crypto.constants.RSA_PKCS1_OAEP_PADDING</code>.</li>
</ul>
</li>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> A new <code>Buffer</code> with the decrypted content.</li>
</ul>
<p>Decrypts <code>buffer</code> with <code>privateKey</code>. <code>buffer</code> was previously encrypted using
the corresponding public key, for example using <a href="#crypto_crypto_publicencrypt_key_buffer"><code>crypto.publicEncrypt()</code></a>.</p>
<p>If <code>privateKey</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if
<code>privateKey</code> had been passed to <a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey()</code></a>. If it is an
object, the <code>padding</code> property can be passed. Otherwise, this function uses
<code>RSA_PKCS1_OAEP_PADDING</code>.</p>
<h4><code>crypto.privateEncrypt(privateKey, buffer)</code><span><a class="mark" href="#crypto_crypto_privateencrypt_privatekey_buffer" id="crypto_crypto_privateencrypt_privatekey_buffer">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.6.0</td>
<td><p>This function now supports key objects.</p></td></tr>
<tr><td>v1.1.0</td>
<td><p><span>Added in: v1.1.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>privateKey</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a> A PEM encoded private key.</li>
<li><code>passphrase</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> An optional passphrase for the private key.</li>
<li><code>padding</code> <a href="crypto.html#crypto_crypto_constants_1" class="type">&#x3C;crypto.constants></a> An optional padding value defined in
<code>crypto.constants</code>, which may be: <code>crypto.constants.RSA_NO_PADDING</code> or
<code>crypto.constants.RSA_PKCS1_PADDING</code>.</li>
</ul>
</li>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> A new <code>Buffer</code> with the encrypted content.</li>
</ul>
<p>Encrypts <code>buffer</code> with <code>privateKey</code>. The returned data can be decrypted using
the corresponding public key, for example using <a href="#crypto_crypto_publicdecrypt_key_buffer"><code>crypto.publicDecrypt()</code></a>.</p>
<p>If <code>privateKey</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if
<code>privateKey</code> had been passed to <a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey()</code></a>. If it is an
object, the <code>padding</code> property can be passed. Otherwise, this function uses
<code>RSA_PKCS1_PADDING</code>.</p>
<h4><code>crypto.publicDecrypt(key, buffer)</code><span><a class="mark" href="#crypto_crypto_publicdecrypt_key_buffer" id="crypto_crypto_publicdecrypt_key_buffer">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v11.6.0</td>
<td><p>This function now supports key objects.</p></td></tr>
<tr><td>v1.1.0</td>
<td><p><span>Added in: v1.1.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>passphrase</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> An optional passphrase for the private key.</li>
<li><code>padding</code> <a href="crypto.html#crypto_crypto_constants_1" class="type">&#x3C;crypto.constants></a> An optional padding value defined in
<code>crypto.constants</code>, which may be: <code>crypto.constants.RSA_NO_PADDING</code> or
<code>crypto.constants.RSA_PKCS1_PADDING</code>.</li>
</ul>
</li>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> A new <code>Buffer</code> with the decrypted content.</li>
</ul>
<p>Decrypts <code>buffer</code> with <code>key</code>.<code>buffer</code> was previously encrypted using
the corresponding private key, for example using <a href="#crypto_crypto_privateencrypt_privatekey_buffer"><code>crypto.privateEncrypt()</code></a>.</p>
<p>If <code>key</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if
<code>key</code> had been passed to <a href="#crypto_crypto_createpublickey_key"><code>crypto.createPublicKey()</code></a>. If it is an
object, the <code>padding</code> property can be passed. Otherwise, this function uses
<code>RSA_PKCS1_PADDING</code>.</p>
<p>Because RSA public keys can be derived from private keys, a private key may
be passed instead of a public key.</p>
<h4><code>crypto.publicEncrypt(key, buffer)</code><span><a class="mark" href="#crypto_crypto_publicencrypt_key_buffer" id="crypto_crypto_publicencrypt_key_buffer">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v12.11.0</td>
<td><p>The <code>oaepLabel</code> option was added.</p></td></tr>
<tr><td>v12.9.0</td>
<td><p>The <code>oaepHash</code> option was added.</p></td></tr>
<tr><td>v11.6.0</td>
<td><p>This function now supports key objects.</p></td></tr>
<tr><td>v0.11.14</td>
<td><p><span>Added in: v0.11.14</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a>
<ul>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a> A PEM encoded public or private key.</li>
<li><code>oaepHash</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The hash function to use for OAEP padding and MGF1.
<strong>Default:</strong> <code>'sha1'</code></li>
<li><code>oaepLabel</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> The label to use for OAEP
padding. If not specified, no label is used.</li>
<li><code>passphrase</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> An optional passphrase for the private key.</li>
<li><code>padding</code> <a href="crypto.html#crypto_crypto_constants_1" class="type">&#x3C;crypto.constants></a> An optional padding value defined in
<code>crypto.constants</code>, which may be: <code>crypto.constants.RSA_NO_PADDING</code>,
<code>crypto.constants.RSA_PKCS1_PADDING</code>, or
<code>crypto.constants.RSA_PKCS1_OAEP_PADDING</code>.</li>
</ul>
</li>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> A new <code>Buffer</code> with the encrypted content.</li>
</ul>
<p>Encrypts the content of <code>buffer</code> with <code>key</code> and returns a new
<a href="buffer.html"><code>Buffer</code></a> with encrypted content. The returned data can be decrypted using
the corresponding private key, for example using <a href="#crypto_crypto_privatedecrypt_privatekey_buffer"><code>crypto.privateDecrypt()</code></a>.</p>
<p>If <code>key</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if
<code>key</code> had been passed to <a href="#crypto_crypto_createpublickey_key"><code>crypto.createPublicKey()</code></a>. If it is an
object, the <code>padding</code> property can be passed. Otherwise, this function uses
<code>RSA_PKCS1_OAEP_PADDING</code>.</p>
<p>Because RSA public keys can be derived from private keys, a private key may
be passed instead of a public key.</p>
<h4><code>crypto.randomBytes(size[, callback])</code><span><a class="mark" href="#crypto_crypto_randombytes_size_callback" id="crypto_crypto_randombytes_size_callback">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v9.0.0</td>
<td><p>Passing <code>null</code> as the <code>callback</code> argument now throws <code>ERR_INVALID_CALLBACK</code>.</p></td></tr>
<tr><td>v0.5.8</td>
<td><p><span>Added in: v0.5.8</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a>
<ul>
<li><code>err</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>buf</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> if the <code>callback</code> function is not provided.</li>
</ul>
<p>Generates cryptographically strong pseudo-random data. The <code>size</code> argument
is a number indicating the number of bytes to generate.</p>
<p>If a <code>callback</code> function is provided, the bytes are generated asynchronously
and the <code>callback</code> function is invoked with two arguments: <code>err</code> and <code>buf</code>.
If an error occurs, <code>err</code> will be an <code>Error</code> object; otherwise it is <code>null</code>. The
<code>buf</code> argument is a <a href="buffer.html"><code>Buffer</code></a> containing the generated bytes.</p>
<pre><code class="language-js"><span class="hljs-comment">// Asynchronous</span>
<span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
crypto.<span class="hljs-title function_">randomBytes</span>(<span class="hljs-number">256</span>, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`<span class="hljs-subst">${buf.length}</span> bytes of random data: <span class="hljs-subst">${buf.toString(<span class="hljs-string">'hex'</span>)}</span>`</span>);
});</code></pre>
<p>If the <code>callback</code> function is not provided, the random bytes are generated
synchronously and returned as a <a href="buffer.html"><code>Buffer</code></a>. An error will be thrown if
there is a problem generating the bytes.</p>
<pre><code class="language-js"><span class="hljs-comment">// Synchronous</span>
<span class="hljs-keyword">const</span> buf = crypto.<span class="hljs-title function_">randomBytes</span>(<span class="hljs-number">256</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(
  <span class="hljs-string">`<span class="hljs-subst">${buf.length}</span> bytes of random data: <span class="hljs-subst">${buf.toString(<span class="hljs-string">'hex'</span>)}</span>`</span>);</code></pre>
<p>The <code>crypto.randomBytes()</code> method will not complete until there is
sufficient entropy available.
This should normally never take longer than a few milliseconds. The only time
when generating the random bytes may conceivably block for a longer period of
time is right after boot, when the whole system is still low on entropy.</p>
<p>This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the
<a href="cli.html#cli_uv_threadpool_size_size"><code>UV_THREADPOOL_SIZE</code></a> documentation for more information.</p>
<p>The asynchronous version of <code>crypto.randomBytes()</code> is carried out in a single
threadpool request. To minimize threadpool task length variation, partition
large <code>randomBytes</code> requests when doing so as part of fulfilling a client
request.</p>
<h4><code>crypto.randomFillSync(buffer[, offset][, size])</code><span><a class="mark" href="#crypto_crypto_randomfillsync_buffer_offset_size" id="crypto_crypto_randomfillsync_buffer_offset_size">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>buffer</code> argument may be any <code>TypedArray</code> or <code>DataView</code>.</p></td></tr>
<tr><td>v7.10.0, v6.13.0</td>
<td><p><span>Added in: v7.10.0, v6.13.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> Must be supplied.</li>
<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <strong>Default:</strong> <code>0</code></li>
<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <strong>Default:</strong> <code>buffer.length - offset</code></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> The object passed as <code>buffer</code> argument.</li>
</ul>
<p>Synchronous version of <a href="#crypto_crypto_randomfill_buffer_offset_size_callback"><code>crypto.randomFill()</code></a>.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(crypto.<span class="hljs-title function_">randomFillSync</span>(buf).<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));

crypto.<span class="hljs-title function_">randomFillSync</span>(buf, <span class="hljs-number">5</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));

<span class="hljs-comment">// The above is equivalent to the following:</span>
crypto.<span class="hljs-title function_">randomFillSync</span>(buf, <span class="hljs-number">5</span>, <span class="hljs-number">5</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));</code></pre>
<p>Any <code>TypedArray</code> or <code>DataView</code> instance may be passed as <code>buffer</code>.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> a = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>32<span class="hljs-built_in">Array</span>(<span class="hljs-number">10</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(crypto.<span class="hljs-title function_">randomFillSync</span>(a).<span class="hljs-property">buffer</span>,
                        a.<span class="hljs-property">byteOffset</span>, a.<span class="hljs-property">byteLength</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));

<span class="hljs-keyword">const</span> b = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Float</span>64<span class="hljs-built_in">Array</span>(<span class="hljs-number">10</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(crypto.<span class="hljs-title function_">randomFillSync</span>(b).<span class="hljs-property">buffer</span>,
                        b.<span class="hljs-property">byteOffset</span>, b.<span class="hljs-property">byteLength</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));

<span class="hljs-keyword">const</span> c = <span class="hljs-keyword">new</span> <span class="hljs-title class_">DataView</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">ArrayBuffer</span>(<span class="hljs-number">10</span>));
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(crypto.<span class="hljs-title function_">randomFillSync</span>(c).<span class="hljs-property">buffer</span>,
                        c.<span class="hljs-property">byteOffset</span>, c.<span class="hljs-property">byteLength</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));</code></pre>
<h4><code>crypto.randomFill(buffer[, offset][, size], callback)</code><span><a class="mark" href="#crypto_crypto_randomfill_buffer_offset_size_callback" id="crypto_crypto_randomfill_buffer_offset_size_callback">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>buffer</code> argument may be any <code>TypedArray</code> or <code>DataView</code>.</p></td></tr>
<tr><td>v7.10.0, v6.13.0</td>
<td><p><span>Added in: v7.10.0, v6.13.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a> Must be supplied.</li>
<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <strong>Default:</strong> <code>0</code></li>
<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <strong>Default:</strong> <code>buffer.length - offset</code></li>
<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> <code>function(err, buf) {}</code>.</li>
</ul>
<p>This function is similar to <a href="#crypto_crypto_randombytes_size_callback"><code>crypto.randomBytes()</code></a> but requires the first
argument to be a <a href="buffer.html"><code>Buffer</code></a> that will be filled. It also
requires that a callback is passed in.</p>
<p>If the <code>callback</code> function is not provided, an error will be thrown.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>);
crypto.<span class="hljs-title function_">randomFill</span>(buf, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
});

crypto.<span class="hljs-title function_">randomFill</span>(buf, <span class="hljs-number">5</span>, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
});

<span class="hljs-comment">// The above is equivalent to the following:</span>
crypto.<span class="hljs-title function_">randomFill</span>(buf, <span class="hljs-number">5</span>, <span class="hljs-number">5</span>, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
});</code></pre>
<p>Any <code>TypedArray</code> or <code>DataView</code> instance may be passed as <code>buffer</code>.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> a = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>32<span class="hljs-built_in">Array</span>(<span class="hljs-number">10</span>);
crypto.<span class="hljs-title function_">randomFill</span>(a, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(buf.<span class="hljs-property">buffer</span>, buf.<span class="hljs-property">byteOffset</span>, buf.<span class="hljs-property">byteLength</span>)
    .<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
});

<span class="hljs-keyword">const</span> b = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Float</span>64<span class="hljs-built_in">Array</span>(<span class="hljs-number">10</span>);
crypto.<span class="hljs-title function_">randomFill</span>(b, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(buf.<span class="hljs-property">buffer</span>, buf.<span class="hljs-property">byteOffset</span>, buf.<span class="hljs-property">byteLength</span>)
    .<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
});

<span class="hljs-keyword">const</span> c = <span class="hljs-keyword">new</span> <span class="hljs-title class_">DataView</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">ArrayBuffer</span>(<span class="hljs-number">10</span>));
crypto.<span class="hljs-title function_">randomFill</span>(c, <span class="hljs-function">(<span class="hljs-params">err, buf</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(buf.<span class="hljs-property">buffer</span>, buf.<span class="hljs-property">byteOffset</span>, buf.<span class="hljs-property">byteLength</span>)
    .<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));
});</code></pre>
<p>This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the
<a href="cli.html#cli_uv_threadpool_size_size"><code>UV_THREADPOOL_SIZE</code></a> documentation for more information.</p>
<p>The asynchronous version of <code>crypto.randomFill()</code> is carried out in a single
threadpool request. To minimize threadpool task length variation, partition
large <code>randomFill</code> requests when doing so as part of fulfilling a client
request.</p>
<h4><code>crypto.randomInt([min, ]max[, callback])</code><span><a class="mark" href="#crypto_crypto_randomint_min_max_callback" id="crypto_crypto_randomint_min_max_callback">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v14.10.0</span>
</div>
<ul>
<li><code>min</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Start of random range (inclusive). <strong>Default</strong>: <code>0</code>.</li>
<li><code>max</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> End of random range (exclusive).</li>
<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> <code>function(err, n) {}</code>.</li>
</ul>
<p>Return a random integer <code>n</code> such that <code>min &#x3C;= n &#x3C; max</code>.  This
implementation avoids <a href="https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#Modulo_bias">modulo bias</a>.</p>
<p>The range (<code>max - min</code>) must be less than 2<sup>48</sup>. <code>min</code> and <code>max</code> must
be <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger">safe integers</a>.</p>
<p>If the <code>callback</code> function is not provided, the random integer is
generated synchronously.</p>
<pre><code class="language-js"><span class="hljs-comment">// Asynchronous</span>
crypto.<span class="hljs-title function_">randomInt</span>(<span class="hljs-number">3</span>, <span class="hljs-function">(<span class="hljs-params">err, n</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`Random number chosen from (0, 1, 2): <span class="hljs-subst">${n}</span>`</span>);
});</code></pre>
<pre><code class="language-js"><span class="hljs-comment">// Synchronous</span>
<span class="hljs-keyword">const</span> n = crypto.<span class="hljs-title function_">randomInt</span>(<span class="hljs-number">3</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`Random number chosen from (0, 1, 2): <span class="hljs-subst">${n}</span>`</span>);</code></pre>
<pre><code class="language-js"><span class="hljs-comment">// With `min` argument</span>
<span class="hljs-keyword">const</span> n = crypto.<span class="hljs-title function_">randomInt</span>(<span class="hljs-number">1</span>, <span class="hljs-number">7</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`The dice rolled: <span class="hljs-subst">${n}</span>`</span>);</code></pre>
<h4><code>crypto.randomUUID([options])</code><span><a class="mark" href="#crypto_crypto_randomuuid_options" id="crypto_crypto_randomuuid_options">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v14.17.0</span>
</div>
<ul>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>disableEntropyCache</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> By default, to improve performance,
Node.js generates and caches enough random data to generate up to
128 random UUIDs. To generate a UUID without using the cache, set
<code>disableEntropyCache</code> to <code>true</code>. <strong>Defaults</strong>: <code>false</code>.</li>
</ul>
</li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Generates a random <a href="https://www.rfc-editor.org/rfc/rfc4122.txt">RFC 4122</a> version 4 UUID. The UUID is generated using a
cryptographic pseudorandom number generator.</p>
<h4><code>crypto.scrypt(password, salt, keylen[, options], callback)</code><span><a class="mark" href="#crypto_crypto_scrypt_password_salt_keylen_options_callback" id="crypto_crypto_scrypt_password_salt_keylen_options_callback">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v12.8.0, v10.17.0</td>
<td><p>The <code>maxmem</code> value can now be any safe integer.</p></td></tr>
<tr><td>v10.9.0</td>
<td><p>The <code>cost</code>, <code>blockSize</code> and <code>parallelization</code> option names have been added.</p></td></tr>
<tr><td>v10.5.0</td>
<td><p><span>Added in: v10.5.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>password</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>salt</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>keylen</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>cost</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> CPU/memory cost parameter. Must be a power of two greater
than one. <strong>Default:</strong> <code>16384</code>.</li>
<li><code>blockSize</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Block size parameter. <strong>Default:</strong> <code>8</code>.</li>
<li><code>parallelization</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Parallelization parameter. <strong>Default:</strong> <code>1</code>.</li>
<li><code>N</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Alias for <code>cost</code>. Only one of both may be specified.</li>
<li><code>r</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Alias for <code>blockSize</code>. Only one of both may be specified.</li>
<li><code>p</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Alias for <code>parallelization</code>. Only one of both may be specified.</li>
<li><code>maxmem</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Memory upper bound. It is an error when (approximately)
<code>128 * N * r > maxmem</code>. <strong>Default:</strong> <code>32 * 1024 * 1024</code>.</li>
</ul>
</li>
<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a>
<ul>
<li><code>err</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>derivedKey</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
</li>
</ul>
<p>Provides an asynchronous <a href="https://en.wikipedia.org/wiki/Scrypt">scrypt</a> implementation. Scrypt is a password-based
key derivation function that is designed to be expensive computationally and
memory-wise in order to make brute-force attacks unrewarding.</p>
<p>The <code>salt</code> should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See <a href="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf">NIST SP 800-132</a> for details.</p>
<p>The <code>callback</code> function is called with two arguments: <code>err</code> and <code>derivedKey</code>.
<code>err</code> is an exception object when key derivation fails, otherwise <code>err</code> is
<code>null</code>. <code>derivedKey</code> is passed to the callback as a <a href="buffer.html"><code>Buffer</code></a>.</p>
<p>An exception is thrown when any of the input arguments specify invalid values
or types.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-comment">// Using the factory defaults.</span>
crypto.<span class="hljs-title function_">scrypt</span>(<span class="hljs-string">'password'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">64</span>, <span class="hljs-function">(<span class="hljs-params">err, derivedKey</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(derivedKey.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));  <span class="hljs-comment">// '3745e48...08d59ae'</span>
});
<span class="hljs-comment">// Using a custom N parameter. Must be a power of two.</span>
crypto.<span class="hljs-title function_">scrypt</span>(<span class="hljs-string">'password'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">64</span>, { <span class="hljs-attr">N</span>: <span class="hljs-number">1024</span> }, <span class="hljs-function">(<span class="hljs-params">err, derivedKey</span>) =></span> {
  <span class="hljs-keyword">if</span> (err) <span class="hljs-keyword">throw</span> err;
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(derivedKey.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));  <span class="hljs-comment">// '3745e48...aa39b34'</span>
});</code></pre>
<h4><code>crypto.scryptSync(password, salt, keylen[, options])</code><span><a class="mark" href="#crypto_crypto_scryptsync_password_salt_keylen_options" id="crypto_crypto_scryptsync_password_salt_keylen_options">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v12.8.0, v10.17.0</td>
<td><p>The <code>maxmem</code> value can now be any safe integer.</p></td></tr>
<tr><td>v10.9.0</td>
<td><p>The <code>cost</code>, <code>blockSize</code> and <code>parallelization</code> option names have been added.</p></td></tr>
<tr><td>v10.5.0</td>
<td><p><span>Added in: v10.5.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>password</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>salt</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>keylen</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a></li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>cost</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> CPU/memory cost parameter. Must be a power of two greater
than one. <strong>Default:</strong> <code>16384</code>.</li>
<li><code>blockSize</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Block size parameter. <strong>Default:</strong> <code>8</code>.</li>
<li><code>parallelization</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Parallelization parameter. <strong>Default:</strong> <code>1</code>.</li>
<li><code>N</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Alias for <code>cost</code>. Only one of both may be specified.</li>
<li><code>r</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Alias for <code>blockSize</code>. Only one of both may be specified.</li>
<li><code>p</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Alias for <code>parallelization</code>. Only one of both may be specified.</li>
<li><code>maxmem</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Memory upper bound. It is an error when (approximately)
<code>128 * N * r > maxmem</code>. <strong>Default:</strong> <code>32 * 1024 * 1024</code>.</li>
</ul>
</li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
<p>Provides a synchronous <a href="https://en.wikipedia.org/wiki/Scrypt">scrypt</a> implementation. Scrypt is a password-based
key derivation function that is designed to be expensive computationally and
memory-wise in order to make brute-force attacks unrewarding.</p>
<p>The <code>salt</code> should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See <a href="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf">NIST SP 800-132</a> for details.</p>
<p>An exception is thrown when key derivation fails, otherwise the derived key is
returned as a <a href="buffer.html"><code>Buffer</code></a>.</p>
<p>An exception is thrown when any of the input arguments specify invalid values
or types.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);
<span class="hljs-comment">// Using the factory defaults.</span>
<span class="hljs-keyword">const</span> key1 = crypto.<span class="hljs-title function_">scryptSync</span>(<span class="hljs-string">'password'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">64</span>);
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(key1.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));  <span class="hljs-comment">// '3745e48...08d59ae'</span>
<span class="hljs-comment">// Using a custom N parameter. Must be a power of two.</span>
<span class="hljs-keyword">const</span> key2 = crypto.<span class="hljs-title function_">scryptSync</span>(<span class="hljs-string">'password'</span>, <span class="hljs-string">'salt'</span>, <span class="hljs-number">64</span>, { <span class="hljs-attr">N</span>: <span class="hljs-number">1024</span> });
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(key2.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>));  <span class="hljs-comment">// '3745e48...aa39b34'</span></code></pre>
<h4><code>crypto.setEngine(engine[, flags])</code><span><a class="mark" href="#crypto_crypto_setengine_engine_flags" id="crypto_crypto_setengine_engine_flags">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v0.11.11</span>
</div>
<ul>
<li><code>engine</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>flags</code> <a href="crypto.html#crypto_crypto_constants_1" class="type">&#x3C;crypto.constants></a> <strong>Default:</strong> <code>crypto.constants.ENGINE_METHOD_ALL</code></li>
</ul>
<p>Load and set the <code>engine</code> for some or all OpenSSL functions (selected by flags).</p>
<p><code>engine</code> could be either an id or a path to the engine's shared library.</p>
<p>The optional <code>flags</code> argument uses <code>ENGINE_METHOD_ALL</code> by default. The <code>flags</code>
is a bit field taking one of or a mix of the following flags (defined in
<code>crypto.constants</code>):</p>
<ul>
<li><code>crypto.constants.ENGINE_METHOD_RSA</code></li>
<li><code>crypto.constants.ENGINE_METHOD_DSA</code></li>
<li><code>crypto.constants.ENGINE_METHOD_DH</code></li>
<li><code>crypto.constants.ENGINE_METHOD_RAND</code></li>
<li><code>crypto.constants.ENGINE_METHOD_EC</code></li>
<li><code>crypto.constants.ENGINE_METHOD_CIPHERS</code></li>
<li><code>crypto.constants.ENGINE_METHOD_DIGESTS</code></li>
<li><code>crypto.constants.ENGINE_METHOD_PKEY_METHS</code></li>
<li><code>crypto.constants.ENGINE_METHOD_PKEY_ASN1_METHS</code></li>
<li><code>crypto.constants.ENGINE_METHOD_ALL</code></li>
<li><code>crypto.constants.ENGINE_METHOD_NONE</code></li>
</ul>
<p>The flags below are deprecated in OpenSSL-1.1.0.</p>
<ul>
<li><code>crypto.constants.ENGINE_METHOD_ECDH</code></li>
<li><code>crypto.constants.ENGINE_METHOD_ECDSA</code></li>
<li><code>crypto.constants.ENGINE_METHOD_STORE</code></li>
</ul>
<h4><code>crypto.setFips(bool)</code><span><a class="mark" href="#crypto_crypto_setfips_bool" id="crypto_crypto_setfips_bool">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v10.0.0</span>
</div>
<ul>
<li><code>bool</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> <code>true</code> to enable FIPS mode.</li>
</ul>
<p>Enables the FIPS compliant crypto provider in a FIPS-enabled Node.js build.
Throws an error if FIPS mode is not available.</p>
<h4><code>crypto.sign(algorithm, data, key)</code><span><a class="mark" href="#crypto_crypto_sign_algorithm_data_key" id="crypto_crypto_sign_algorithm_data_key">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.2.0, v12.16.0</td>
<td><p>This function now supports IEEE-P1363 DSA and ECDSA signatures.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p><span>Added in: v12.0.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Null_type" class="type">&#x3C;null></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Undefined_type" class="type">&#x3C;undefined></a></li>
<li><code>data</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a></li>
</ul>
<p>Calculates and returns the signature for <code>data</code> using the given private key and
algorithm. If <code>algorithm</code> is <code>null</code> or <code>undefined</code>, then the algorithm is
dependent upon the key type (especially Ed25519 and Ed448).</p>
<p>If <code>key</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if <code>key</code> had been
passed to <a href="#crypto_crypto_createprivatekey_key"><code>crypto.createPrivateKey()</code></a>. If it is an object, the following
additional properties can be passed:</p>
<ul>
<li>
<p><code>dsaEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> For DSA and ECDSA, this option specifies the
format of the generated signature. It can be one of the following:</p>
<ul>
<li><code>'der'</code> (default): DER-encoded ASN.1 signature structure encoding <code>(r, s)</code>.</li>
<li><code>'ieee-p1363'</code>: Signature format <code>r || s</code> as proposed in IEEE-P1363.</li>
</ul>
</li>
<li>
<p><code>padding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Optional padding value for RSA, one of the following:</p>
<ul>
<li><code>crypto.constants.RSA_PKCS1_PADDING</code> (default)</li>
<li><code>crypto.constants.RSA_PKCS1_PSS_PADDING</code></li>
</ul>
<p><code>RSA_PKCS1_PSS_PADDING</code> will use MGF1 with the same hash function
used to sign the message as specified in section 3.1 of <a href="https://www.rfc-editor.org/rfc/rfc4055.txt">RFC 4055</a>.</p>
</li>
<li>
<p><code>saltLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Salt length for when padding is
<code>RSA_PKCS1_PSS_PADDING</code>. The special value
<code>crypto.constants.RSA_PSS_SALTLEN_DIGEST</code> sets the salt length to the digest
size, <code>crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN</code> (default) sets it to the
maximum permissible value.</p>
</li>
</ul>
<h4><code>crypto.timingSafeEqual(a, b)</code><span><a class="mark" href="#crypto_crypto_timingsafeequal_a_b" id="crypto_crypto_timingsafeequal_a_b">#</a></span></h4>
<div class="api_metadata">
<span>Added in: v6.6.0</span>
</div>
<ul>
<li><code>a</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>b</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a></li>
</ul>
<p>This function is based on a constant-time algorithm.
Returns true if <code>a</code> is equal to <code>b</code>, without leaking timing information that
would allow an attacker to guess one of the values. This is suitable for
comparing HMAC digests or secret values like authentication cookies or
<a href="https://www.w3.org/TR/capability-urls/">capability urls</a>.</p>
<p><code>a</code> and <code>b</code> must both be <code>Buffer</code>s, <code>TypedArray</code>s, or <code>DataView</code>s, and they
must have the same byte length.</p>
<p>If at least one of <code>a</code> and <code>b</code> is a <code>TypedArray</code> with more than one byte per
entry, such as <code>Uint16Array</code>, the result will be computed using the platform
byte order.</p>
<p>Use of <code>crypto.timingSafeEqual</code> does not guarantee that the <em>surrounding</em> code
is timing-safe. Care should be taken to ensure that the surrounding code does
not introduce timing vulnerabilities.</p>
<h4><code>crypto.verify(algorithm, data, key, signature)</code><span><a class="mark" href="#crypto_crypto_verify_algorithm_data_key_signature" id="crypto_crypto_verify_algorithm_data_key_signature">#</a></span></h4>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v13.2.0, v12.16.0</td>
<td><p>This function now supports IEEE-P1363 DSA and ECDSA signatures.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p><span>Added in: v12.0.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>algorithm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Null_type" class="type">&#x3C;null></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Undefined_type" class="type">&#x3C;undefined></a></li>
<li><code>data</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="crypto.html#crypto_class_keyobject" class="type">&#x3C;KeyObject></a></li>
<li><code>signature</code> <a href="buffer.html#buffer_class_buffer" class="type">&#x3C;Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type">&#x3C;TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type">&#x3C;DataView></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a></li>
</ul>
<p>Verifies the given signature for <code>data</code> using the given key and algorithm. If
<code>algorithm</code> is <code>null</code> or <code>undefined</code>, then the algorithm is dependent upon the
key type (especially Ed25519 and Ed448).</p>
<p>If <code>key</code> is not a <a href="#crypto_class_keyobject"><code>KeyObject</code></a>, this function behaves as if <code>key</code> had been
passed to <a href="#crypto_crypto_createpublickey_key"><code>crypto.createPublicKey()</code></a>. If it is an object, the following
additional properties can be passed:</p>
<ul>
<li>
<p><code>dsaEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> For DSA and ECDSA, this option specifies the
format of the signature. It can be one of the following:</p>
<ul>
<li><code>'der'</code> (default): DER-encoded ASN.1 signature structure encoding <code>(r, s)</code>.</li>
<li><code>'ieee-p1363'</code>: Signature format <code>r || s</code> as proposed in IEEE-P1363.</li>
</ul>
</li>
<li>
<p><code>padding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Optional padding value for RSA, one of the following:</p>
<ul>
<li><code>crypto.constants.RSA_PKCS1_PADDING</code> (default)</li>
<li><code>crypto.constants.RSA_PKCS1_PSS_PADDING</code></li>
</ul>
<p><code>RSA_PKCS1_PSS_PADDING</code> will use MGF1 with the same hash function
used to sign the message as specified in section 3.1 of <a href="https://www.rfc-editor.org/rfc/rfc4055.txt">RFC 4055</a>.</p>
</li>
<li>
<p><code>saltLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;integer></a> Salt length for when padding is
<code>RSA_PKCS1_PSS_PADDING</code>. The special value
<code>crypto.constants.RSA_PSS_SALTLEN_DIGEST</code> sets the salt length to the digest
size, <code>crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN</code> (default) sets it to the
maximum permissible value.</p>
</li>
</ul>
<p>The <code>signature</code> argument is the previously calculated signature for the <code>data</code>.</p>
<p>Because public keys can be derived from private keys, a private key or a public
key may be passed for <code>key</code>.</p>
</section><section><h3>Notes<span><a class="mark" href="#crypto_notes" id="crypto_notes">#</a></span></h3>
<h4>Legacy streams API (prior to Node.js 0.10)<span><a class="mark" href="#crypto_legacy_streams_api_prior_to_node_js_0_10" id="crypto_legacy_streams_api_prior_to_node_js_0_10">#</a></span></h4>
<p>The Crypto module was added to Node.js before there was the concept of a
unified Stream API, and before there were <a href="buffer.html"><code>Buffer</code></a> objects for handling
binary data. As such, the many of the <code>crypto</code> defined classes have methods not
typically found on other Node.js classes that implement the <a href="stream.html">streams</a>
API (e.g. <code>update()</code>, <code>final()</code>, or <code>digest()</code>). Also, many methods accepted
and returned <code>'latin1'</code> encoded strings by default rather than <code>Buffer</code>s. This
default was changed after Node.js v0.8 to use <a href="buffer.html"><code>Buffer</code></a> objects by default
instead.</p>
<h4>Recent ECDH changes<span><a class="mark" href="#crypto_recent_ecdh_changes" id="crypto_recent_ecdh_changes">#</a></span></h4>
<p>Usage of <code>ECDH</code> with non-dynamically generated key pairs has been simplified.
Now, <a href="#crypto_ecdh_setprivatekey_privatekey_encoding"><code>ecdh.setPrivateKey()</code></a> can be called with a preselected private key
and the associated public point (key) will be computed and stored in the object.
This allows code to only store and provide the private part of the EC key pair.
<a href="#crypto_ecdh_setprivatekey_privatekey_encoding"><code>ecdh.setPrivateKey()</code></a> now also validates that the private key is valid for
the selected curve.</p>
<p>The <a href="#crypto_ecdh_setpublickey_publickey_encoding"><code>ecdh.setPublicKey()</code></a> method is now deprecated as its inclusion in the
API is not useful. Either a previously stored private key should be set, which
automatically generates the associated public key, or <a href="#crypto_ecdh_generatekeys_encoding_format"><code>ecdh.generateKeys()</code></a>
should be called. The main drawback of using <a href="#crypto_ecdh_setpublickey_publickey_encoding"><code>ecdh.setPublicKey()</code></a> is that
it can be used to put the ECDH key pair into an inconsistent state.</p>
<h4>Support for weak or compromised algorithms<span><a class="mark" href="#crypto_support_for_weak_or_compromised_algorithms" id="crypto_support_for_weak_or_compromised_algorithms">#</a></span></h4>
<p>The <code>crypto</code> module still supports some algorithms which are already
compromised and are not currently recommended for use. The API also allows
the use of ciphers and hashes with a small key size that are too weak for safe
use.</p>
<p>Users should take full responsibility for selecting the crypto
algorithm and key size according to their security requirements.</p>
<p>Based on the recommendations of <a href="https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar1.pdf">NIST SP 800-131A</a>:</p>
<ul>
<li>MD5 and SHA-1 are no longer acceptable where collision resistance is
required such as digital signatures.</li>
<li>The key used with RSA, DSA, and DH algorithms is recommended to have
at least 2048 bits and that of the curve of ECDSA and ECDH at least
224 bits, to be safe to use for several years.</li>
<li>The DH groups of <code>modp1</code>, <code>modp2</code> and <code>modp5</code> have a key size
smaller than 2048 bits and are not recommended.</li>
</ul>
<p>See the reference for other recommendations and details.</p>
<h4>CCM mode<span><a class="mark" href="#crypto_ccm_mode" id="crypto_ccm_mode">#</a></span></h4>
<p>CCM is one of the supported <a href="https://en.wikipedia.org/wiki/Authenticated_encryption">AEAD algorithms</a>. Applications which use this
mode must adhere to certain restrictions when using the cipher API:</p>
<ul>
<li>The authentication tag length must be specified during cipher creation by
setting the <code>authTagLength</code> option and must be one of 4, 6, 8, 10, 12, 14 or
16 bytes.</li>
<li>The length of the initialization vector (nonce) <code>N</code> must be between 7 and 13
bytes (<code>7 ≤ N ≤ 13</code>).</li>
<li>The length of the plaintext is limited to <code>2 ** (8 * (15 - N))</code> bytes.</li>
<li>When decrypting, the authentication tag must be set via <code>setAuthTag()</code> before
calling <code>update()</code>.
Otherwise, decryption will fail and <code>final()</code> will throw an error in
compliance with section 2.6 of <a href="https://www.rfc-editor.org/rfc/rfc3610.txt">RFC 3610</a>.</li>
<li>Using stream methods such as <code>write(data)</code>, <code>end(data)</code> or <code>pipe()</code> in CCM
mode might fail as CCM cannot handle more than one chunk of data per instance.</li>
<li>When passing additional authenticated data (AAD), the length of the actual
message in bytes must be passed to <code>setAAD()</code> via the <code>plaintextLength</code>
option.
Many crypto libraries include the authentication tag in the ciphertext,
which means that they produce ciphertexts of the length
<code>plaintextLength + authTagLength</code>. Node.js does not include the authentication
tag, so the ciphertext length is always <code>plaintextLength</code>.
This is not necessary if no AAD is used.</li>
<li>As CCM processes the whole message at once, <code>update()</code> can only be called
once.</li>
<li>Even though calling <code>update()</code> is sufficient to encrypt/decrypt the message,
applications <em>must</em> call <code>final()</code> to compute or verify the
authentication tag.</li>
</ul>
<pre><code class="language-js"><span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'crypto'</span>);

<span class="hljs-keyword">const</span> key = <span class="hljs-string">'keykeykeykeykeykeykeykey'</span>;
<span class="hljs-keyword">const</span> nonce = crypto.<span class="hljs-title function_">randomBytes</span>(<span class="hljs-number">12</span>);

<span class="hljs-keyword">const</span> aad = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'0123456789'</span>, <span class="hljs-string">'hex'</span>);

<span class="hljs-keyword">const</span> cipher = crypto.<span class="hljs-title function_">createCipheriv</span>(<span class="hljs-string">'aes-192-ccm'</span>, key, nonce, {
  <span class="hljs-attr">authTagLength</span>: <span class="hljs-number">16</span>
});
<span class="hljs-keyword">const</span> plaintext = <span class="hljs-string">'Hello world'</span>;
cipher.<span class="hljs-title function_">setAAD</span>(aad, {
  <span class="hljs-attr">plaintextLength</span>: <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">byteLength</span>(plaintext)
});
<span class="hljs-keyword">const</span> ciphertext = cipher.<span class="hljs-title function_">update</span>(plaintext, <span class="hljs-string">'utf8'</span>);
cipher.<span class="hljs-title function_">final</span>();
<span class="hljs-keyword">const</span> tag = cipher.<span class="hljs-title function_">getAuthTag</span>();

<span class="hljs-comment">// Now transmit { ciphertext, nonce, tag }.</span>

<span class="hljs-keyword">const</span> decipher = crypto.<span class="hljs-title function_">createDecipheriv</span>(<span class="hljs-string">'aes-192-ccm'</span>, key, nonce, {
  <span class="hljs-attr">authTagLength</span>: <span class="hljs-number">16</span>
});
decipher.<span class="hljs-title function_">setAuthTag</span>(tag);
decipher.<span class="hljs-title function_">setAAD</span>(aad, {
  <span class="hljs-attr">plaintextLength</span>: ciphertext.<span class="hljs-property">length</span>
});
<span class="hljs-keyword">const</span> receivedPlaintext = decipher.<span class="hljs-title function_">update</span>(ciphertext, <span class="hljs-literal">null</span>, <span class="hljs-string">'utf8'</span>);

<span class="hljs-keyword">try</span> {
  decipher.<span class="hljs-title function_">final</span>();
} <span class="hljs-keyword">catch</span> (err) {
  <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">error</span>(<span class="hljs-string">'Authentication failed!'</span>);
  <span class="hljs-keyword">return</span>;
}

<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(receivedPlaintext);</code></pre>
</section><section><h3>Crypto constants<span><a class="mark" href="#crypto_crypto_constants_1" id="crypto_crypto_constants_1">#</a></span></h3>
<p>The following constants exported by <code>crypto.constants</code> apply to various uses of
the <code>crypto</code>, <code>tls</code>, and <code>https</code> modules and are generally specific to OpenSSL.</p>
<h4>OpenSSL options<span><a class="mark" href="#crypto_openssl_options" id="crypto_openssl_options">#</a></span></h4>
<table>
  <tbody><tr>
    <th>Constant</th>
    <th>Description</th>
  </tr>
  <tr>
    <td><code>SSL_OP_ALL</code></td>
    <td>Applies multiple bug workarounds within OpenSSL. See
    <a href="https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html">https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html</a>
    for detail.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_ALLOW_NO_DHE_KEX</code></td>
    <td>Instructs OpenSSL to allow a non-[EC]DHE-based key exchange mode
    for TLS v1.3</td>
  </tr>
  <tr>
    <td><code>SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION</code></td>
    <td>Allows legacy insecure renegotiation between OpenSSL and unpatched
    clients or servers. See
    <a href="https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html">https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html</a>.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_CIPHER_SERVER_PREFERENCE</code></td>
    <td>Attempts to use the server's preferences instead of the client's when
    selecting a cipher. Behavior depends on protocol version. See
    <a href="https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html">https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html</a>.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_CISCO_ANYCONNECT</code></td>
    <td>Instructs OpenSSL to use Cisco's "speshul" version of DTLS_BAD_VER.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_COOKIE_EXCHANGE</code></td>
    <td>Instructs OpenSSL to turn on cookie exchange.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_CRYPTOPRO_TLSEXT_BUG</code></td>
    <td>Instructs OpenSSL to add server-hello extension from an early version
    of the cryptopro draft.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS</code></td>
    <td>Instructs OpenSSL to disable a SSL 3.0/TLS 1.0 vulnerability
    workaround added in OpenSSL 0.9.6d.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_EPHEMERAL_RSA</code></td>
    <td>Instructs OpenSSL to always use the tmp_rsa key when performing RSA
    operations.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_LEGACY_SERVER_CONNECT</code></td>
    <td>Allows initial connection to servers that do not support RI.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_MICROSOFT_SESS_ID_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_MSIE_SSLV2_RSA_PADDING</code></td>
    <td>Instructs OpenSSL to disable the workaround for a man-in-the-middle
    protocol-version vulnerability in the SSL 2.0 server implementation.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NETSCAPE_CA_DN_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_NETSCAPE_CHALLENGE_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_COMPRESSION</code></td>
    <td>Instructs OpenSSL to disable support for SSL/TLS compression.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_ENCRYPT_THEN_MAC</code></td>
    <td>Instructs OpenSSL to disable encrypt-then-MAC.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_QUERY_MTU</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_RENEGOTIATION</code></td>
    <td>Instructs OpenSSL to disable renegotiation.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION</code></td>
    <td>Instructs OpenSSL to always start a new session when performing
    renegotiation.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_SSLv2</code></td>
    <td>Instructs OpenSSL to turn off SSL v2</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_SSLv3</code></td>
    <td>Instructs OpenSSL to turn off SSL v3</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_TICKET</code></td>
    <td>Instructs OpenSSL to disable use of RFC4507bis tickets.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_TLSv1</code></td>
    <td>Instructs OpenSSL to turn off TLS v1</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_TLSv1_1</code></td>
    <td>Instructs OpenSSL to turn off TLS v1.1</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_TLSv1_2</code></td>
    <td>Instructs OpenSSL to turn off TLS v1.2</td>
  </tr>
  <tr>
    <td><code>SSL_OP_NO_TLSv1_3</code></td>
    <td>Instructs OpenSSL to turn off TLS v1.3</td>
  </tr>
    <tr><td><code>SSL_OP_PKCS1_CHECK_1</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_PKCS1_CHECK_2</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_PRIORITIZE_CHACHA</code></td>
    <td>Instructs OpenSSL server to prioritize ChaCha20Poly1305
    when client does.
    This option has no effect if
    <code>SSL_OP_CIPHER_SERVER_PREFERENCE</code>
    is not enabled.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_SINGLE_DH_USE</code></td>
    <td>Instructs OpenSSL to always create a new key when using
    temporary/ephemeral DH parameters.</td>
  </tr>
  <tr>
    <td><code>SSL_OP_SINGLE_ECDH_USE</code></td>
    <td>Instructs OpenSSL to always create a new key when using
    temporary/ephemeral ECDH parameters.</td>
  </tr>
    <tr><td><code>SSL_OP_SSLEAY_080_CLIENT_DH_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_TLS_BLOCK_PADDING_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_TLS_D5_BUG</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>SSL_OP_TLS_ROLLBACK_BUG</code></td>
    <td>Instructs OpenSSL to disable version rollback attack detection.</td>
  </tr>
</tbody></table>
<h4>OpenSSL engine constants<span><a class="mark" href="#crypto_openssl_engine_constants" id="crypto_openssl_engine_constants">#</a></span></h4>
<table>
  <tbody><tr>
    <th>Constant</th>
    <th>Description</th>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_RSA</code></td>
    <td>Limit engine usage to RSA</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_DSA</code></td>
    <td>Limit engine usage to DSA</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_DH</code></td>
    <td>Limit engine usage to DH</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_RAND</code></td>
    <td>Limit engine usage to RAND</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_EC</code></td>
    <td>Limit engine usage to EC</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_CIPHERS</code></td>
    <td>Limit engine usage to CIPHERS</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_DIGESTS</code></td>
    <td>Limit engine usage to DIGESTS</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_PKEY_METHS</code></td>
    <td>Limit engine usage to PKEY_METHDS</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_PKEY_ASN1_METHS</code></td>
    <td>Limit engine usage to PKEY_ASN1_METHS</td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_ALL</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>ENGINE_METHOD_NONE</code></td>
    <td></td>
  </tr>
</tbody></table>
<h4>Other OpenSSL constants<span><a class="mark" href="#crypto_other_openssl_constants" id="crypto_other_openssl_constants">#</a></span></h4>
<p>See the <a href="https://wiki.openssl.org/index.php/List_of_SSL_OP_Flags#Table_of_Options">list of SSL OP Flags</a> for details.</p>
<table>
  <tbody><tr>
    <th>Constant</th>
    <th>Description</th>
  </tr>
  <tr>
    <td><code>DH_CHECK_P_NOT_SAFE_PRIME</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>DH_CHECK_P_NOT_PRIME</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>DH_UNABLE_TO_CHECK_GENERATOR</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>DH_NOT_SUITABLE_GENERATOR</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>ALPN_ENABLED</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_PKCS1_PADDING</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_SSLV23_PADDING</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_NO_PADDING</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_PKCS1_OAEP_PADDING</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_X931_PADDING</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_PKCS1_PSS_PADDING</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>RSA_PSS_SALTLEN_DIGEST</code></td>
    <td>Sets the salt length for <code>RSA_PKCS1_PSS_PADDING</code> to the
        digest size when signing or verifying.</td>
  </tr>
  <tr>
    <td><code>RSA_PSS_SALTLEN_MAX_SIGN</code></td>
    <td>Sets the salt length for <code>RSA_PKCS1_PSS_PADDING</code> to the
        maximum permissible value when signing data.</td>
  </tr>
  <tr>
    <td><code>RSA_PSS_SALTLEN_AUTO</code></td>
    <td>Causes the salt length for <code>RSA_PKCS1_PSS_PADDING</code> to be
        determined automatically when verifying a signature.</td>
  </tr>
  <tr>
    <td><code>POINT_CONVERSION_COMPRESSED</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>POINT_CONVERSION_UNCOMPRESSED</code></td>
    <td></td>
  </tr>
  <tr>
    <td><code>POINT_CONVERSION_HYBRID</code></td>
    <td></td>
  </tr>
</tbody></table>
<h4>Node.js crypto constants<span><a class="mark" href="#crypto_node_js_crypto_constants" id="crypto_node_js_crypto_constants">#</a></span></h4>
<table>
  <tbody><tr>
    <th>Constant</th>
    <th>Description</th>
  </tr>
  <tr>
    <td><code>defaultCoreCipherList</code></td>
    <td>Specifies the built-in default cipher list used by Node.js.</td>
  </tr>
  <tr>
    <td><code>defaultCipherList</code></td>
    <td>Specifies the active default cipher list used by the current Node.js
    process.</td>
  </tr>
</tbody></table></section>
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